Narcissus, in the Market Square area, is a great shop that offers swimsuits by all the hot brands such as Juicy Couture, Lilly Pulitzer, and more, and it also has lingerie by On Gossamer and other higher-end brands. It also has an extensive variety of higher-end clothing by Lilly Pulitzer, James Jeans, and other boutique brands. Prices are not all that great; I can get Juicy Couture for cheaper at Nordstrom; but their big sales are hard to beat. They also have shoes and flip flops, beachwear, jewelry, and Kama Sutra items. They even have Lilly Pulitzer for kids there, both for swim and for playwear.
The salespeople range from very helpful to not helpful at all, depending on who you get. One may get the impression that the store has gotten so big that they really don't need your business, but again, it depends on the salesperson. Some are extremely helpful. The dressing rooms are ample and there is even a box of toys for kids to play with while their moms are trying on things. The place is very well organized.
If you are looking for a great swimsuit, don't hesitate to check Narcissus out. If you want one that is a great deal, go in August. They are very good at displaying sale signs in their windows and advertising their big sales.