Slightly OT, but one of the best things I ever did was to get a bra fitted properly by a specialist shop. Had been going to a department store previously but they got it completely wrong. Has really made a difference (went from 22 DD to a 16G!)

As for buying bras and underwear that go together - only time I did this was for my wedding. Now I just buy for practicality. I think I feel more sexy with my outer wear.