Go for a good fit, not fitted

Because your bust is much larger than your waist, you don't want a tight fit -- a shirt like this Cotton-silk lawn twisted-placket shirt, $68 at J.Crew, is perfect. Having darts put under the bust is inexpensive and can make a world of difference. Also look for fabrics that offer a bit of weight -- too flimsy and your girls will look like they're on the loose!