At our Club, we utilize CSI Software. It has a more analytical base, and is designed well for mutli-site facilities. For a studio or facility specific to personal training, there is MindBody, which has a great user interface, is web-based, and makes it simple to book appointments online. Those are the two that I am most familiar with. Hope this helps!
Depends on how much you want to pay but there are two that I like to use both are in different price ranges. Mindbody.com and┬áhttp://www.fitsw.com/. Mindbody was very nice and professionally done – the only downside was that it’s pricey. FitSW seems more tailored for individual trainers / smaller gyms because its free – just not quite as polished as Mindbody but still very good. Both Fitsw and mindbody have excellent ways to track progress on your client’s fitness and they both do a great job at creating and recording workout plans and diet plans. They both are very helpful in helping me manage all my client’s info in one location.