@Hog1 - yeah, that Westin is nuts...my wife and I went in the lobby just to look around and it was incredible.
The hotel I stayed in is linked above, and is part of a
group of inns in Key West. It was nice place, quiet, and convenient.
The closer to Mallory Square/Marina you stay, the more expensive it gets. I'd say the average hotel rate will be around $200/night if not more, depending on when you arrive and leave. If you stay for a week, I'd strongly suggest looking into condo/house rentals. You'll pay similar prices to a hotel, and have more privacy.