We dove Maui last summer and had a great experience with ScubaShack. They also have condos at Kamaole Sands (on the southwest side), which was great.......all organized through the dive shop.
We rented an older Jeep from Maui Car Rentals, was nervous at first but it was great. It was cheap and waiting for us at the airport, did it all on the internet, it was sweet to ride around Maui with the top down in a non-rental company looking jeep, felt more like a local I guess....
Molokini Crater, Turtle City, Ulua Beach for a night dive.....are must dives, at least in my opinion.........the vis and stuff (big and little) at the crater is awesome. I think April is whale season, so we would live at the crater if we were there.
This is the diver comment we posted on ScubaShack's website:
Great crew, great boat, great dives what more can we say about our Maui experience! Awesome at finding critters and making each dive one to remember seeing the mantas and turtles was the highlight for our daughter. We were treated like one of the family and the boat gear was new, makes travel to the Islands much easier. Way to go. PS. We also loved the condo, great location!
Hope this helps.......M
PS - the note about rental gear is key, their gear was nice and like new, so we traveled light to the Islands....