The Sheraton is conveniently located to the main beach ... so if you're planning on spending a lot of time at the beach, it's a good location ... it's also very close to the airport. It is a little far from the rest of the action ... Duval Street and most of the other sites to see in Key West. This is no problem if you're renting a car ...

The Hilton looks very nice ... it was built since my last time there, but the location is pretty good. The Hyatt probably has the best location of all the hotels you mentioned, followed closely by the Hilton.

The two Wyndham properties were previously Marriotts. The Casa Marina is a very nice old hotel pretty good location, though both Wyndham's are at the side of the island from most of the Duval Street action ... the Reach is kind of bland if you ask me ... don't know a whole lot about it though ...

Personally ... I'd go with the Hilton ...