Joe: The one I can definitely recommend is Hawaii Movie Tours on the island of Kauai. They take you by comfortable air conditioned bus to see sites where movies have been made as well as movie stars homes (incredible beach views at Bette Middler's home on the beach at Hanalei Bay). Lots of movies have been made on this island.
CruiseTimer: for MAUI, I have done both the road to Hana and the Molokini snorkel. First, I would recommend you check with parks and wildlife to see if there has been a lack if rain. If so, the "7 Sacred Pools" will likely be dry or low and mosquito ridden. This is what happened to us when we got to the end of the "Road to Hana." Also, there is a hike required to the 7 Sacred Pools and you WILL need some hiking shoes. Pack your lunch lightly because you will be hauling it up a steep hike. That being said, I think the pools would be beautiful if full of water but lots of people go so know that you will be sharing..However, the actual drive up the road provides nothing but stunning views of the island the entire time. You will want to get out of the car and take pics a lot. However, there is not much to do/see except the view during the drive to Hana..nothing. The drive takes quite some time and to try to do the Road to Hana AND the Molokini snorkel in one day (even though u have til midnight) will be asking a lot. The road is single lane and dangerous to navigate during the day..much less at night. ALL of this being said...If it were me..Knowing what I know..Having done both...I would choose the Molokini snorkel first - solely because I have snorkeled ALL over the place (Caribbean and Hawaiian islands) and that was the most beautiful snorkel I have ever had..the fish the most colorful & gorgeous, the water the most pristine, sighting of rare monk seals playing, turtles, whales and funniest of all..Being chased briefly by a Hawaiian Barracuda. I would do the snorkel and then spend the rest of the day at a southern beach (Makena area or further south). There is a snorkel tour for Molokini that leaves from Big Makena beach (I've been on it several times - good tour, good captain who has been doing it many yrs). I've been to Maui 4 times and driven all over the island several times. Good luck; hope you have a blast!!