We reserved a jet ski island tour with Barefoot Billy's and it was fantastic! Tour guide (dark hair, dark round sunglasses) was thorough, gave great directions, and wasn't uptight. The water was fairly calm, so we got to go as fast as the machines would go, got mine to 54mph! The freetime in the gulf was exceptional, clear glass like conditions, made for a lot of fast fun and maneuvering. We traveled 28 miles over 90 minutes with 6 stops along the way to learn some history and pointers about our visit. Suggest doing this on one of your first days, the guides are water concierges!
The location is hard to find, its behind the Waldorf Astoria and the gate is locked, so you have to shout over it to the attendant to get access. Little akward.
Highly recommend.