I hear the lagoon side of Molokini is better? Thanks for the tip about VRBO. Wow, there's a ton of deals on there! Since we have to wait before flying, we have to spend at least one day topside. I'm not all about nightlife, but I'd like it to be interesting...
I have made 3 trips to Hawaii. Dove for a week off Maui X2 and also the Big Island X2.
Maui over-all will give you great topside and good diving (at Molokini), clear water there. I loved the backside of Molokini better, Reefs End on the frontside was a great dive spot though. There are plenty of sight seeing opportunities on Maui; theres a bike trip down the mountain (you can coast nearly the whole 38 miles), helicopter trips, the road to Hana, we've stayed at Kaanaplai area twice. We've rented a Harley, we've searched out waterfalls. Watch the wind surfers on the north side, snorkel at BlackRock. Don't forget about a Lau with local dancers and food. Lahina is within a couple of miles where there's plenty to eat and people watch/shop.
On the Big Island for budget there's the Kona Tiki, on the ocean older 50's/60's style hotel. The cost somewhere around $80 per night. Things to do: #1 Manta night dive ( in our top ten dives that we've done and we've well over 1000 dives), #2 rent a car (which you'll have to do most any place in Hawaii) and travel to the north side to see the earth being formed by the volcano, it's awesome. Plenty of waterfalls to see, you can helicopter here as well.
We were there 1 year ago and spent a day snorkeling with 21 dolphins in the Bay not too far from the captain Cook memorial.
Most recently my wife and I spent some time in the Keys and the diving was NOT spectacular as it was very windy and viz was about 10ft (although previously we've had some good diving, its the roll of the dice in Florida). There are some things to do topside but nothing compared to the beauty of Hawaii. Maui would be our first choice with the Big Island not far behind.
The Kona Tiki:
Near snorkeling on the Big Island
Kaanapali's beach near Black Rock
Kaanaapli sunset cruise: