I have found the Anytime Fitness located in the Bishop Arts District of North Oak Cliff to be a little gem of a gym. It has all new equipment (individual TV's on every piece of cardio equipment), 24 hr access, reasonable fees, and a very approachable and helpful staff (no hardcore sales pitches). It is has served me well, from the days I wanted to do hardcore weightlifting to other days when I wanted to just stretch and get my heart rate up. Regardless of where you are in your level of fitness young or old, in shape or out, experienced or not, I think you will find Anytime Fitness a very comfortable and welcoming spot to seek more health in your life.
Pros: 24 Hour Access Gym, Helpful Staff, Fees are reasonable