Molokini Crater
I was there for 15 days last year. There is so many options for Snorkeling, but the big one is the above image. I really recommend renting a car if you are there for awhile.
Lahina (spelling?) is great and is home to cheesburgers in paradise, which is a great burger place. Oh and you can golf at the city courses for 40 bucks a round during the week.
Also the pool bar at the Hyatt, has a bar in the cave (in the pool) while you watch sports and drink alcohol with fruit on it. Unreal!