We are leaving for 2 weeks in Maui and Kauai. In the interest of packing lightly, should I bring hiking shoes or gym shoes for hiking on both islands? I have searched other posts and can't find any information. We will do moderate hikes...nothing too easy or difficult. It's our first visit, so we aren't familiar with the terrain.
Also, do we need to pack bug spray?
Thanks so much for your help!

I hiked in regular tennis shoes. I would buy bug spray in HI rather than risk a discharge into my luggage and then I'd leave it there. That's one product I would not want on my stuff, it's stinky and oily!

I wore these for all our hiking - great for muddy, watery trails, crossing streams, walking the rocky beaches, etc. I got a cheap version at Walmart, have also seen them at Target.
http://tinyurl.com/yf2xdy
Brought those, a pair of regular gym shoes for horsebackriding and ziplining, and then two pairs of sandals for everyday wear, and a pair of flip flops for the pool.

Some people recommend bringing a ratty pair of gymshoes for hiking the trails and then just tossing them before coming home, since some of the dirt is a lovely red color.

We were in Kauai in September. We wore Tevas for all of our hikes except one. We hiked the Kalalau Trail to Hanakapiai Beach and then to the Falls, the trail to the bottom of Opaekaa Falls, and several other trails in Tevas. They had good traction on the slippery, steep, rocky trails and we could just walk in the water when we had to cross streams. We wore our hiking boots when we did the Pihea trail into the Alakai swamp. There were no streams to cross and we appreciated the ankle support. We are used to steep hikes but on relatively smooth trails. The trails we hiked in Kauai were alomst all very rocky, so there was more scrambling and large steps up and down and picking your way through the rocks than we are used to. And lots of mud! And yes, bring or buy mosquito repellant. Getting out and hiking was one of the highlights of our trip. Have a great time!

I'm all for packing light but in Kauai I would definitely recommend a pair of amphibious hiking shoes. The terrain really is too rough for plain sneakers and many of the best hikes have stream crossings (like the one off the Kalalau trail that goes to Hanakapiai Falls). You'll also want something you can easily hose off or throw in the washer.

I picked up these before our trip and loved them:
http://www.zappos.com/n/p/dp/2911970/c/59209.html

Have you heard of the Red Dirt shirts? They come from Kauai. Your shoes are going to get muddy, dirty and will most likely not return the same color you brought them.

If we're planning on hiking on our trips to Hawaii we pack some hiking boots esp. for traction if it starts to rain. If your tennis shoes have good tread they might be ok. Do you have lightweight hiking shoes?