I agree that it depends on the person. Back in 2000-2003 BC (before kids), I used go to the gym regularly. I did a lot of the group aerobic classes and weight work using the machines. I loved it. That's what worked best for me THEN.
Nowadays, though, different situation and a whole different ballgame. I have 3 kids and I find what works best for me is to workout during naptime. I'm not a morning person right now, so I get my workouts done when my baby is napping, my preschooler is having quiet time and my first grader is at school. I honestly don't believe I would be as dedicated about exercise, as I am now, if I had to get the kids in the car each day, drive over to the gym, pay for daycare at the gym for my kids, etc, etc. I also think I would have a lot less time in my day for other things.
Another reason, and perhaps my biggest one of all, that I prefer home workouts over the gym is that I honestly believe I get a BETTER workout at home. I think back on the aerobics classes I used to do at the gym, and compared to Cathe, they pale in comparison! Add to that ... I now do free weights (thanks to Cathe) and I have much greater muscle definition than I ever achieved using the machines at the gym.
Besides Cathe workouts, I also enjoy running. I prefer to run outside as I hate the treadmill, but I hate the cold and windy North Dakota winters even more. Running outside in the winter is not something I want to do right now, so I choose the lesser of two evils: the treadmill. I usually end up joining a gym for a few months during the winter (Jan-March, for example) so I can get some runs in and to train for the May race events they have in my town. Even then, I just tack on my running at the gym to my regular Cathe workout schedule, doing my runs in the evening when I can have my husband watch my kids instead of dragging them over to the gym daycare.
Bottom line. I don't think I will ever, ever, ever be a fulltime dedicated gym member again. I like my Cathe workouts WAY too much. However, until I own a treadmill of my own (someday! someday!) I will be utilizing the gym on a seasonal basis, if only so I can get my runs in.