First of all, every Bally's is different. You can always go check it out and get a tour and ask all the questions you want. I will say that chains like Bally and 24 hr are more of a meat market. If you're worried about being surrounded by fitness buffs and meat heads, I wouldn't join Bally. Most gyms do not have "overnight" lockers...in fact they'll cut your lock off if you leave it on.
I'm not sure on prices for Bally, but if you have an LA Fitness close, they are very reasonable. Now days, most gyms don't make you sign a contract either, so if you join and hate it...no problem...just find another gym.
I would definitely visit a few places you're considering, because feeling at home in your gym is important. The more you like the atmosphere, the more likely you will continue to go. Sometimes, choosing the closest to your house is the best bet, as convenience will also play a huge role at some point.
Once you get settled, search for a workout partner. This will help prolong your stay and get you in a great routine! Good luck, and remember to make it fun!