Where do you live? If you're in CA, you may be in luck. The one place that comes to mind is Harbin Hot Springs (about 1.5 hrs. north of San Francisco). It is a co-ed outdoor hot springs facility that is clothing optional (which means about 99% naked). The patrons are all across the board from young, hot and beautiful to older and more beautiful on the inside than out. ;-) Anyway, the locker room where everybody changes to go into the pools is co-ed. It is not really a sexual place, but there is certainly a lot of "checking out" going on. It's kind of fun to see women undress at a locker since that's certainly not a sight that men have the pleasure of seeing on a regular basis (and vice-versa). Check it out on your next trip to NorCal!