I hadn't addressed this thread because I am not a bigger triathlete. Well, actually I am but not in a way that I need more support from my tri suit. I'm glad this thread got bumped up so that some of our more curvy triathletes can comment.

As for the pro suits. A lot of serious triathletes build up enough of a thickening on their sit bones that padding is no longer an issue and for some of us more padding means more chafing. So I am personally much more comfortable with a very minimal chamois. I ride that way all the time now, not just when I race. The one piece suits are nice because they don't expose your low back on the bike and help to protect the skin. As for going to the bathroom... pro triathletes will pee in their suit before they will stop for a potty break. For guys, they can stop and hike up one short leg, hang it out the bottom and away they go. I don't know any women that have managed a similar technique though I suppose it might be possible. If you think you'll need to use the porta jon during a race, get a two piece.

I race with a two piece that I wear under my wet suit. That way at transition I have only shoes, wetsuit and helmet issues to worry about. Makes life much easier.