If we visit a club or a hotel that has one, we play in it. Both of us have never cum in one but we find it sensual and fun and its usually a precursor to moving to a room for full play.
Yes, done it! Not in a fully public place, but outside hot tub at someone's home. Problem is that the water takes away the good properties of a woman's (and man's) personal lubricant! So it isn't as HOT as one might think. Still fun though.