I just got back from a 3 weeks vacation - split up the weeks between Oahu, BI, and Maui. I struggled with whether I should take my 50D and lenses, or take the SX10 IS. I opted to take the SX10 IS for portability.
Hey, check out the Hertz in Maui. They've got a red Corvette convertible you can rent, if this is your speed.
Don't forget to see Hawaii from the air. It is a totally amazing experience. Check out Blue Hawaiian. We used them for all three islands and they were fantastic.
P.S. Any L-O-S-T fans?