Check out the Hyatt at the Bellevue in Philadelphia... there is a Michael Graves designed gym there (Sporting Club at the Bellevue) which is free to Hyatt guests regardless of status. I'm planning a staycation there myself over the 4th of July weekend with a buddy from NYC. Another friend of mine belongs to the Sporting Club and loves it... he's a big swimmer as well.

Here's a link to the Hyatt website which indicates the benefit.

http://philadelphia.bellevue.hyatt.c...eActId=1830071