Push up cups?

I agree about working with your alterations person on this -- a professional will know exactly what will make your dress fit best. Daughter is typically a thin 36 DD, the LAST thing she expected was needing push-up cups in her dress. However, because of the dress construction (tons of boning and a very structured bodice), her alterations lady actually added two sets of cups/pads -- a set of push-up cups that "lifted" her a little and then a second small set that helped ensure she fit perfectly into the dress' structure since there was no way she could wear a bra and she wanted to feel very "secure" when dancing, etc. They had to play with the placement of the cups, because she didn't want them to push her chest up and in to give her a bunch of cleavage, but once they got everything in exactly the right place, it was perfect. Good alterations are worth their cost!

I very rarely wear a normal bra anymore. I opt for bralettes and sports bras because I always look bulky when I wear a push up. They put push up cups in when I found my dress and I hated it. All personal preference. Try both and see what makes you feel good!