If you are considering an ATV tour, I've done one on both Kauai and BI. Kipu ATV on Kauai was the best. Napali Catamaran out of Hanalei was FABULOUS but I'm going to try Napali SeaBreeze in about two weeks and will post something when I return to compare them. The only snorkeling trip I have taken was a night snorkel to see Manta's on BI which was cool but the BEST snorkeling I have experienced was not a tour but walk in at Shark's Cove on Oahu. Kahaluu on BI was also very good. I was not impressed with Hanauma Bay - didn't see any fish and it was pretty rough the day I went. Of all the activities during our trips my favorite activity was probably Napali Catamaran (despite a little seasickness).

PS - The Waipio Valley horseback ride was great!

I have not been to Kauai, but have been to the other three islands.

Oahu - Japanese influence is greatest here. I loved the Byodo-In Temple and dinner at Haiku along the rail (and walking in their little garden). If you are interested in windsurfing, this is best on this island near Kailua. Oahu is also best for do it yourself hikes if you get a good book for hiking. Matsumoto Shave Ice. Lanikai beach. Pearl Harbor.

Maui - I loved the nightly free shows at the Kaanapali Beach Hotel more than any other shows I've been to on the islands. If you are daring, parasailing down Haleakala is a recommendation. Do NOT ride a bike down Haleakala. Horseback riding into the crater is one-of-a-kind for this island. The Road to Hana is unique for this island. Also, the hike the Pipiwai Trail and get to Oheo Gulch early in the morning before crowds arrive. I'o Needle. Shave Ice at Tom's Mini Mart in Wailuku. If you want to ride a boat just for views from the water and want to visit Lanai, take a ferry to Lanai...cheap way to do both. Snorkeling from shore is best here. Get a good book on snorkeling...I liked the areas to the far south the best. Loved Big Beach as far as beaches go. If you want to kayak, I recommend that here at the Pali Sea Cliffs...you'll also get in some snorkeling.

Big Island - Volcanoes National Park, Hawaii Tropical Garden, Mauna Kea observatories, horseback or hike Waipio Valley and/or hike Polulu Valley. Snorkel at Place of Refuge. Spend an evening exploring the small town of Hawi. If you want to swim with dolphins, I think this is only available on the Big Island. There is also a tour for swimming with manta rays at night - Highly recommend. Exploring lava tubes.

Helicopter rides - I haven't done one, but have investigated on all islands. I wouldn't do it on Oahu, but any of the other islands would be good. If you aren't going to hike out to the lava on the Big Island, and only want to do one, I would choose to do that on the Big Island to see the lava (provided it's flowing).

Ziplines - none on Oahu or The Big Island. There are 2 on Maui. I didn't do either one, but thought about doing the more northern one and hiking the trails nearby. I read better reviews of that one. Don't know what the one on Kauai is like.

Marginal - yes you are right about the lava - it is several miles across the lava field from the end of Chain of Craters road, but only about a mile from Kalapana (still need flashlights etc!) But it is still worth driving down Chain of Craters road, amongst all that lava and new land - and you can see the steam from the lava entering the ocean from there. It's interesting to see it from both sides!

Ziplines - I'm pretty sure there's one on Big Island now, but I can't remember where. I saw a sign for 'new zipline now open' or something and joked about it (as there's no way I would try it!) I think it was probably along the Kohala coast somewhere.

There is a new zipline on the Big Island in North Kohala. http://www.bigislandecoadventures.com/ I hear it's really fun!

I have taken both the Blue Hawaiian island-wide helicopter tour, and a shorter helicopter tour out of Hilo just over the volcano, which was much cheaper, and I think that's a good option especially if you also take a helicopter ride in Kauai.

I have a take on ziplines - DO NOT do them anywhere in Hawaii .. Wait till u go to Costa Rica ... after all they r pioneers and it is more value for your money in some of the lushest forests you would see...

I have been to Big Island, Kauai and Maui.
I would not cram too many paid activities in any island.
Unique to Big Island - lava lava and lava - do not pay for any tours to see this. Diving/snorkeling anywhere on Big Island (depending on ur budget u can get very good snorkeling for free - refer the snorkel Hawaii guide for all the islands) . Punaluu beach/Place of refuge - to see turtles. Waipio, polulu, Akaka for photo ops.

Unique to Maui -
Nakalele Blowhole (there is one in Kauai too But i liked seeing both). THe drive on the morth side is very pretty.
Haleakala natioanl park on both sides - we did the pipiwai trail, sliding sands and halemalu trail. Recommend the Pipiwai trail.
Road to Hana - Spends 3 days doing both north and south including the pipiwai hike.
Some boat trip - lot of dolphins on the way to molokini - however molokini is over rated. so this is not a must do paid activity.
Kauai
Napali Napali and Napali - by air, by boat and by hikes. All are worth it ... Also remember Kokee is actually more of seeing Napali. Waimea is okay but Kokee is exceptional.
Refer the SNorkel Kauai guide. We snorkeled in TUnnels, Kee, Lydgate an pua pua. Tunnels and Kee were very nice. Please snorkel in high tide ONLY. good for both the reefs and you.

ATVs etc are so unnecessary to enjoy these beautiful islands. Take advantage of the fact that Hawaii is in US and we have a good park system. So the hikes, beach activities (snorkeling included), drive etc are free and in fact the best things to enjoy in the island.
Enjoy!

to save more money, you could consider camping in any of the islands.

Any day I would vote for snorkeling over submarines ...

Also please do not support shark feeding or playing with dolphins type activities. Shark feeding disrupts the ocean ecosystem and endangers humans as they start associating humans with food. Dolphin type activities happen in a captive environment and however they sugarcoat it that is the horrible truth.

I did a manta ray dive on the BI & though they did not appear that night, it was still worth the trip.

Also, on Kauai, we did the Princeville Stables horse ride tour to picnic/swim at a waterfall. You actually park the horses & hike in part of the way. We loved it!

We enjoyed the Kipu ATV tour on Kauai as well.

On the Big Island, we hiked 2 1/4 miles in (flat but bumpy road/ground in site of the water the whole way) to the Green Sand Beach. This was such a ethereal & special place that I highly recommend it! You can drive to it if you have 4 wheel drive. We did not, but some friendly folk gave us a ride part of the way back & the road is so bumpy that you have to drive very slowly.

Also did the Kalaulau Trail on Kauai to the first beach ( another 2 mile or so hike). This one is more challenging than the Green Sand Beach as it climbs up & back down. Such wonderful views of the ocean/beaches along the way!

Having done both the BI & Kauai heli tours I would recommend the BI one if, like is stated above, you don't hike out to see the lava (we did not & really 'didn't miss it' after doing the heli tour - I had injured my hip & found walking temporarily uncomfortable that day).

On Kauai, we enjoyed the heli trip, but I think I'd prefer to see the Na Pali Coast with Captain Andy's boat cruise rather than the heli. I'd definitely do one or the other! If I'd been younger, I even would have tried the kayak trip - but was talked out of that one as it is very strenuous!

Regarding the drive on the northside of Maui -
I do recommend this as well, but be very careful not to go beyond the wide two lane road onto the one-lane two-way road. I accidentally did and lived the next hour or so in terror. I tried to back out of it one I realized I'd gone too far, but two cars came behind me and wouldn't back up. I had no option but to squeeze my car between a rocky cliff on the passenger side of the vehicle and the car coming head on that wanted to pass on the driver side without falling over the cliff. It took about twenty minutes (and I was nearly in tears) to get to a point on the other side of the valley where I could turn around...only to go back now on the side of the road where I'd be the one falling off the cliff rather than being squashed into rocks. I seriously contemplated abandoning the car and letting the rental company know where to pick it up. I wouldn't wish that experience on anyone. It was terrifying.

That day could have been worse traffic-wise because the highway was shut down near the aquarium due to a fatality accident and anyone trying to get to the other side of the island would have had to take this route. It was bumper to bumper in both directions -and often that means front bumper to front bumper with drivers trying to negotiate around each other.

This is the only time that I've been cursed at by a local and told to get out of Hawaii....I would have cared if he was actually a native rather than just a local jerk.

<lifeisbeautiful :Any day I would vote for snorkeling over submarines ...>

Maybe not if you can't swim! :)

Lots of great suggestions for you to consider on your visit.

12 days on the Big Island will provide plenty of time to see and experience what the island has to offer. At some point you will probably pass through the town of Captain Cook, a bit south of Kailua-Kona on the west side of the island. A local institution there is the dining room of the Manago Hotel, an interesting place to stop for lunch.

http://www.roadfood.com/Restaurant/R...e-manago-hotel

Oh, I LOVED the north side of Maui trip - all the way around! And, I am not a dare devil sort by any means - will not get on a roller coaster! We did make sure we were going in the direction that allowed our car to be on the 'inside' of the lane. We got the BEST shave ice at a little home stand just around the peak of the island curve called Auntie Ululani's. Here is a link:
http://www.onmyplate.org/2003/12/treats_from_kah.html

I did want to mention that if possible, do your heli tour of Kauai AND your trip to Waimea Canyon on different days. They BOTH are much better in the morning hours - so do them before noon. The clouds tend to roll in & block the views if you don't.
I was warned of this on this board, but ended up having to do both the same day & sure enough, the views in Waimea were blocked by the time we got up there in the afternoon. Again, since I'd just flown over in the heli, it wasn't tragic, but not optimum either.

"to save more money, you could consider camping in any of the islands."

I could also choose to drive splints under my fingernails, but I've decided not to. LOL

Hey, I'm staying in condos -- self catering, no room service, no maid service. That's about as "roughing it" as I care to get this trip!

Thanks again for all these great ideas -- and the comparisons. I need to start making a chart of them.

<<Oh, I LOVED the north side of Maui trip - all the way around! And, I am not a dare devil sort by any means - will not get on a roller coaster!>>

=) And I am the dare devil! I was the one who suggested parasailing down Haleakala! It could very well make a big difference to go on a day when the highway is not shut down in the other direction (I probably naively assumed that people would just wait in traffic or not go anywhere rather than trying to go around the other way). If I hadn't been so scared for my life the day that we went, I would have loved to keep going. It is beautiful over there. But I would have had a panic attack if traffic stayed like that for the entire drive around. If traffic like that is not the norm, then go for it.

NeoPatrick - Make sure you locate the phone numbers to check traffic on each of the islands. On the day that I had this experience, we were actually headed to Haleakala. We hit traffic that wasn't moving and I had the phone number for Maui's traffic saved in my phone, called it and learned that the highway was shut down. So we were able to make a quick decision to turn around and change our plans for the day rather than wonder whether to wait it out or not. Actually, Ijust checked my phone and still have Maui's number saved - 808-986-1200. I'm not positive whether the other islands have a similar service.

Today I had lunch with an old friend (and by "old" I don't just mean we've been friends for a long time -- LOL). I was telling him about my Hawaii trip. He was saying I should skip Maui as there's simply nothing there -- it's dead and dull. I was kind of shocked by that. Finally I asked when the last time was that he was there -- are you ready? -- 1946!!!

I suspect your friend meant to say skip Kauai. Does his name start with a K and end with nine((?))

Hee. Hee. No, actually he loved Kauai -- even back then.

I don't meet your response criteria Patrick, only been to Kauai. But reading the other posts, can tell you, if you (and I hope you do) drive up to the canyon in Kauai, go as early as you can. We got an "early" start by island standards, but drove from the north shore. By the time we got to the top, there was nothing but fog and it was COLD. So no tarrying, go early.

And on Kauai, if I had to make a choice on seeing the Na Pali Coast I would do the boat tour (Catamaran, we used Holoholo) as opposed to the helicopter. There is something about being up close and personal to those cliffs/rock formations, etc.

How I envy your trip. Enjoy, and be sure to update us on your plans. Hope you check out Postcards for a meal in Hanalei.

C