For typical fashion swimsuits, hot tub use will destroy the elastic in short order, making it crumbly. To keep the top from lifting off, you will want a one-piece. Two piece swimsuits are designed to look pretty, but they aren't really practical. Speedo swimsuits tend to be tighter and more durable, so they don't have the bubbling issue as much. (Hold up a Speedo swimsuit and a fashion swimsuit of similar cut and the same size, and see how much smaller the Speedo is. It is much tighter.) Whatever you buy, do follow the advice of others and rinse it well in clean, cool water after every swim in chlorinated water. UV rays will also take a toll, long-term, on the fabric of fashion swimsuits (I can't speak for Speedo suits here).
Thanks, everyone, for the polyester advice! I don't swim often, but I am sick of only getting a few seasons (and five uses) out of a swimsuit, even with proper care.