Ours aren't elevated, but mine are little dogs. One of the water bowls is elevated about 2" off the floor because Charlie likes to stand in it and splash the water out. After we elevated it a little he no longer does it. We have another water bowl in the living room, but he's never splashed in that one.

I was just talking about this with a friend the other day. I told her that if I ever have a large dog I will probably use an elevated dish. I just think they seem more comfortable for the dog. Also if there is any possibility of it helping to prevent bloat then I'm for it. I'd do a bit of research before making my final decision, but I think I'd probably use one.