Let me start this off by saying that I have not been to the gym in almost a year. So if you have been to the gym or even thought about going recently you are already a better person than I am.
It probably depends on the gym you are working out at, but I would think that the gym would be a great place to meet potential dates. But bad news gym rats - you're not going to meet your spouse at the gym. Sadly, all that sweating and grunting where you think you are impressing everyone isn't going to get you any dates.
I know that a lot of people have gym memberships and that there are a lot of options when you are actually at the gym. I also know that 'going to the gym' is not the same as 'working out'. I go to the gym. My wife actually works out.