Last year at camp my son & 2 other campers took 45 minutes in the changing room only to come out with their 'dry' clothes on over their wet suits. Early on this year I took him to the beach one day. It was deserted & well off the beaten path, so I skinny dipped for a few minutes & let him try it when he asked if he could. This got him to be more comfortable being naked outside of the bathroom or his bedroom. We've skinny dipped in the pool at home a few times since then. This year at camp he still wasn't the first one out of the changing room, but he wasn't the last either. He was carrying his wet suit, not wearing it under his clothes this time.
I think my daughters take after my wife, and want no part of it. I've not asked them, nor do I plan to. If they ever do, I doubt they'd do it while I was home.
I don't see the big deal if it's same sex, they've all got the same parts. Co-ed, ehhh... that's going to have a lot of variables to it. Toddlers are different than 17 year olds.
My parents wouldn't have done it (I don't think) nor do I think they would have condoned it, I'm not sure they would have condemned it though. I see no harm in it of itself, it's not a sexual thing.