Because it is so large and requires two separate lodging places to experience its mountains, rain forests, and ocean beaches, ONP should get three full days exclusive of travel time to and from....not sure that you have time for it. I sincerely hope that you will not be able to book a whale-watching tour because the orca population is declining (starving, really) and tour boat noise is a contributor (the orca search for food using echolocation, and boat propellers disturb the way in which sound waves travel under water).

Florence is your destination for dune buggies and horseback riding.

Seven nights is definitely a short time here, especially since you want to go to places that are far apart.

Seattle is wonderful, but do know that hotel prices are insane with cruise season, so you have been warned Seriously, expect at a minimum $300/night. Places do fill up due to this, so start looking now and get that taken care of.

As for ONP, it is a fantastic place, especially in early summer when we still get a great feel for the rainforests. It is generally best if you can allot 3 full days to the park since it is very spread out. You definitely need to book lodging asap and that is very limited as the tourist season is pretty short, so not a ton of options. Do you have an idea of what you want to see here? You will need at least 2 different locations, as one base does not work for this park. Something in/around Port Angeles to see Hurricane Ridge( a must), and then something further west and along the north/south corridor. Hurricane Hill is a nice hike there that is definitely family friendly and you see a lot of marmots etc as well as wildflowers, so keeps the young kids interested. For the next area, our family likes Kalaloch Lodge and it works well for us. They have cabins that do sleep 5, so check into that and see what you think. The Hoh is not to be missed. The Hall of Mosses is short and takes less than 30 minutes, but of course may take longer with a young child. The Hoh River trail is great and is 17 miles one way, but unless you are backpacking of course, you would just go as far as you want and then double back. I normally would not say this, but you could skip this trail and just do the Hall of Mosses and then explore the river bank behind the rangers office. Another area of ONP that is really good, but a further drive, so you would need to prioritize, is Cape Flattery out by Neah Bay.

For an Oregon town with horseback riding, look to Seaside, Cannon Beach or Manzanita, all of which are on the north coast. My own personal favorite is Cannon Beach as has been since I was a little kid growing up here. Look at Sea Ranch RV Park as they have stables and do rides. I haven't done that so cannot personally speak, but see them on the beach. Note that many places here require 2-3 night minimums in the summer. So you may need to work the rest of your trip around this. In CB, our favorite place is the Surfsand Resort, which is right on the water and is the only place along the entire OR coast that has seasonal cabana service. So lots of beach toys, Adirondack chairs/umbrellas set up, etc all for your use. They will also make fires for you and can supply s'more items for an extra charge. They are geared towards families and even though our kids are grown, we still go back there and love it. If that is too pricey or full, take a look at the BlueGull Inn and their 2 bedroom cottage. It has a full kitchen and plenty of beds for a family of 5. It is not right on the water, but less than a block away. It is an older motel that has been redone and is quite nice. There are loads of other places, but these are ones that we have personally stayed at that would work for a family of 5.

For dune buggy adventures you need to head to the central coast around Newport down to Bandon. That is not my thing, so I can't help with that.

As for an itinerary, if you follow my suggestions and head to ONP and then south, then after around Bandon just head straight back up I-5 as that is the fastest route back to the airport. I would suggest flying into Seattle and out of Portland to maximize your time.

Some good advice given by others. Mine would be to fly into PDX and rent a car there and forget the high Seattle hotel prices. If you really must see Seattle (Pike Place market and Space needle) take the train north from Portland to Seattle and see what you came to see and then fly home from SEATAC. There are some cheap motels near the airport for people flying out early the next morning.

tom--Portland hotel prices are not much cheaper than Seattles.

The ones near the airport with shuttles are not as expensive. Portland also has 2 HI Hostels. I've stayed at both of them. Otherwise, head out to Hood River or head straight for Cannon Beach or Seaside.

Tom--Well, yeah, airport hotels are always less than downtown. Seattle has hostels as well. I was comparing apples to apples.

Welcome to Fodor's!

I'm going to give you two maps - google the places on them. Some general thoughts...

As stated, Seattle is very expensive in the summer; even the "cheap" airport-area hotels are quite expensive, driven by the demands of Alaska cruise passengers. In addition, some locations such as Cannon Beach can have 2- or even 3-night minimum stays during the summer, so for a trip in which you want to include Olympic National Park, whale watching and things like dune buggies, time management can become very difficult.

Olympic National Park is very spread out, and the drives between the various tourist highlights tend to be long and boring. With kids the ages of yours, I'm compelled to ask what sorts of activities do you prefer? Most of the park's highlights (Hurricane Ridge, the rain forest valleys, the coastal beaches) involving walks and hikes, some of which might not be super kid-friendly. Is that okay?

Dune buggy rides etc. are located on the south-central Oregon coast (near and south of Florence) and would require much of an extra day in both directions.

The southern resident orca population (those easily seen from Washington and southern British Columbia) are becoming endangered and there are moves to curtail human interaction, so it's entirely possible that whale watching operations in Washington and BC might be restricted (distance from boats to whales, number of boats, etc.) so I wonder if that could be a negotiable item for you.

So here are the maps.

1. https://goo.gl/maps/AdbL5ves82oPVrFQ6 . This begins and ends in Seattle and includes a loop of the Olympic Peninsula, down to Cannon Beach and Cape Disappointment at the awesome mouth of the Columbia River, then back along the river's historic north shore to Mount St. Helens, and a return to Seattle. It also includes a day trip to Victoria BC from Port Angeles (as foot passengers on the Coho ferry) from which you can take one of the reputable whale watching cruises run from Victoria's picturesque Inner Harbour. (Everyone will need passports for this.) The timetable I'd suggest for this would be one night in Seattle, three on the Olympic Peninsula, two on the southern Washington/northern Oregon coast, and one last night on the way back to Seattle.

2. https://goo.gl/maps/SyWkhdcdTCdp2dns9 . This is quite a bit different from the first. It includes neither Seattle nor Olympic National Park. Instead, it starts and ends in Portland and includes the Columbia River Gorge, Maryhill, Hood River and the Hood River Valley, Mount Hood, and finally the coast near the mouth of the Columbia, similar to the first map.

In my view, given the kids' ages, this is a much more kid-friendly plan, and it's worth some research on your part. Features include the many waterfalls along the Columbia Gorge walls, most of them easily accessed by families with kids. The kids can visit Herman the Sturgeon and feed the baby trout at the Bonneville hatchery, go on horseback rides near Hood River (several stables in the area) or splash in several rivers or quiet lakes in the area. Hood River is a charming little town set at the foot of the Hood River Valley with its orchards, vineyards and fields of lavender, with Mount Hood looming over everything. You can take the "Magic Mile" chairlift up to the permanent ice fields on the side of the big volcano, where they'll still be skiing. Visit the funky Maryhill Museum and nearby weird copy of Stonehenge, then head out to Cannon Beach, Seaside and Cape Disappointment before returning to Portland for the flight home.

For this route I'd spend three or four nights in Hood River (where, by the way the weather will likely be warmer and sunnier than farther west) doing day trips to Mount Hood, Maryhill, horseback rides, etc., then a couple out on the coast. My guess is that this would be an easier, possibly cheaper, and equally gratifying week than one where you're in the car a lot of the time.

Do some googling and see what you think. Again, welcome to Fodor's!