Hey, are you in the UK? And define large - large as in 34F or large as in woooooahh out there large?
Try Debenhams and La Senza, both cater for fairly large sizes and usually carry some cute styles. As a guy I can't say I'm a big fan of support (I of course take your point but hey, support just isn't sexy... large but not well supported is soooo much more appealing!) but I suspect both stores will have some options for you if you're not extremely large. Again if you're in the UK I seem to recall La Senza is no longer on the highstreet but I think you'll still be able to order online.
It depends on if you're plus size with large breasts or smaller built but with large breasts. If you're the first, I would try Lane Bryant, Catherine's, or Soma Intimates. If you're the second option, then I would try Nordstrom because I was told they have a wide variety there.