I like the variety
I like the variety of equipment at my gym. I'd have to spend thousands of dollars to even come close at home.
I also enjoy seeing the serious gym babes - That is motivating! ok - a little distracting too, but still motivating - lol
I figure that I save some money just by using their hot water everyday instead of mine! I can take a long shower and not have to be a hypocrite when I tell my kids not to waste so much water at home.
Plus I have a home office, so if I did not go out to the gym, some days I would not leave the house and that would be too much time at home.