Heya, there are two recent-ish threads about this in the women's forum, too. It's a hard call because people feel more comfortable and troll-free about omgzwomenhaveboobies over there, but tri-specific should be over here! I'm going to copy-paste, and you could PM Koffee Brown to get into the "Ladies' Room"....
"I started out with a combo of various options, but came down to a one-piece tri suit with bike shorts, and a quick-drying actual triathlon sports bra under. Yes, it's compression-only, but if you're doing a 1/2 IM, you want the durn thing to dry before the run so you're not chafing. Try everything on for chafing possibilities, and stock up on a lovely product called BodyGlide.
Anyway, links to what I wear :
Zoot is a bit cheaper, and I like their fit, but most stores don't stock their bras so I didn't get a chance to try one on. I firmly believe in that, and will drive over an hour to find stuff to try before buying.
I came to the one-piece
suit because a top rides up, showing my belleh. I also like longer bike shorts, tan line and what not. Wearing the one-piece with a bra enables me to unzip quickly for the portapotty before donning my wetsuit, or to zip up entirely for the bike (no bugs in the cleavage), or to unzip for breathing room on the run. And that is why I wear what I do.
HAVE FUN!"