I'm lucky enough to live in a part of the world where I can run outdoors year-round. Still, I end up using the small fitness room in our apartment building 1-2 times a week. I do hate gyms, and would rather be outside, however. Particularly if I had to drive to get to the gym; it just wouldn't happen. I'd buy a treadmill and a set of weights first. We do, however, drive 10 minutes to get to a hot yoga studio once a week. I enjoy the heat and the yoga and hot yoga is definitely not something I could do at home.
Anyway, I think it really depends on how you like to work out. If you think you'd prefer classes, or having a pool to swim in, then I'd say try out a membership! There is definitely something to be said about being in a fitness-oriented environment, when you can't work up the will-power to exercise on your own!