Always glad to help, MountainDew! Key West has quite a few restaurants that should fit the bill... Louie's Backyard and La Trattoria leap to mind.

Smathers Beach is probably your best bet both for a late night stroll and for daytime sunbathing... but I don't know how private it'll be. The beaches tend to draw everyone on the island. Smathers Beach is on the south side of Key West on South Roosevelt Blvd.

As for waverunners, they run from $35 - $75 an hour at most places. There are also several sailboats that have 3 - 5 hour private sails in the same price range.

Good luck with the crowds at the airport, and just remember, you'll be warming yourself on the beach before you know it!