disneydream'n, don't listen to anyone here....a bikini will be fine, and as for the instructions that the lifeguards give you to cross your arms across your chest, well...thats not necessary either.
Summit Plummit is really not THAT bad...but there is an incredible rush of speed and by the time you hit the bottom trough, you are moving pretty good...I've had an atomic wedgie wearing men's board shorts, so I can imagine most woman's swim wear will do the same. The slide is a lot of fun, and over pretty quickly...the view from the top is great. I guess if I were you (and female), I would be really cautious wearing a two piece. If you do chose to wear one (which I always condone

) just hold on tight to the top by keeping your arms tight across your chest.
Have fun!