Like Diana, I'm not overly concerned about a pretty bra strap peeking out of a neckline or a smidge of a bump. Since I don't wear extremely tight T-shirts or sweaters, any irregularities are pretty minimal. If I am concerned, a couple of lightweight silicone pads fixes the problem instantly. And, since I prefer a three-part cup for its shaping, positioning my breast so the nipple is at the intersection of the seams "hides" any headlight tendencies better than padding would--at least in my experience.
I think the seamed vs. molded preference comes down to aesthetic preferences and breast shape. Like Diana, my ski-slope shaped, wide-spaced breasts look so much better in an underwire, three-piece, balcony bra than they ever did in a molded cup. And my bras definitely don't look matronly--Mr. G appreciation led to his suggestion I completely revamp my undies wardrobe even after I told him the price.
If you are interested, Lisa, I'd head to a good bra shop with a tight white T-shirt in hand and start trying on different styles to see how different bras can give you different shapes when worn under that T-shirt!