Depends on the gym. If it's just a place where you spend 15 bucks a month and there's a bunch of machines you can use, probably not a meeting place. Would perhaps even be creepy and/or rude to talk to others.
But when you're taking classes with people, or it's a crossfit kinda gym that's totally built around a team concept, great place to meet people.
To me, it seems like gym isn't the place. I've been taking group class for over 4 months. I've not made a single friend in this time. People come on time, do the class, pack up their shit quickly and leave.
It is in bay area, and I go-to my company gym which is fairly busy and big.
But when you're taking classes with people, or it's a crossfit kinda gym that's totally built around a team concept, great place to meet people.