The Ramada has an OK gym with weights, rowing machines and all the usual, plus a pleasant pool which allows about 15m straight-line swimming. Annual m'ship is 6,000 for families and 5,000 for singles, all subject to a 375/- registration fee. They also have one, three and six month packages.
Haven't been there for a while, but the Oasis's large gym always seemed a bit scruffy and indifferently maintained and women I knew preferred the greater comfort of the Ramada or Sheraton.
Garveys has a small but clean, new gym, and the Rugby club has a lot of free weights.