Rickster,
You are in for a real treat! If you have never dived when whales are around, get ready for one great experience. They will be there and they will be singing. It is one of nature's uw treats that only we divers can experience in person.
If you get a chance, see if one of the dive shops is doing the back wall of Molokini. I think it is one of the world class dives in the Islands. If you have good bottom times, you can make a live boat drift dive that will offer you many, many wonderful sights--including some small, but gorgeous lionfish.
Maybe the guys can arrange for that. Or you can see if BandB or Ed Robinson are doing that dive.
I will predict something: you will love Maui and want to come back. And I will suggest something: give the Kona Coast on the Big Island a whirl someday.
joewr--singing a bunch of old Harry Owens and the Royal Hawaiins tunes...