During my youth and into early adulthood I, too, was an athlete. After having kids I could not find a gym close enough to my home that had childcare so I opted to not go to any gym. Thus the shape I am in today.
Anyhow, pretty recently, I tried the Curves down the street from my house. I went there twice and decided its not for me. First, as the lady was instructing me on how to use the machines all I could think was this is not proper. The lady said that you want to do each rep as fast as possible to make the machines "hiss". Once you see the machines you will know what I'm talking about. But when I did the reps the way she instructed me I could totally tell that I was not properly engaging the specific muscle I was supposed to be working because the machine was doing too much of the work for me. Second, I found the circuit not to be cardio intensive enough for me.
While I am sure that Curves does work for some women out there, I know that it is not sufficiant enough for my needs. I have since started using The Firm. If you are unfamiliar with The Firm and their line of workout products I would recommend looking them up. At Target you can get The Firm's TransFIRMer on clearange for about $40. It also comes with 3 workout dvds. The Firm is more up my ally. Meaning it uses freeweights (which is optimal over a machine any day) and I work up a sweat, even with the 30 minute workout. It really targets, tones, and burns fat. I can feel my muscles working and getting stronger. Please be aware that The Firm's newest product is The TransFIRMation and I have read many mixed reviews of this product. People tend to love the older versions of The Firm and their products.
Hope this helps.