I have posted these details on a couple of threads but thought i'd start one so as to stop repeating the information.
Like some of you I too am large up top (34G) and have been agonising over what support I can get if I choose to wear a backless dress. I have searched the internet high and low and came accross the Faveo Freedom Bra, it is a strapless, backless bra that is specifically designed for larger ladies 34D and above. It looks a bit odd and not very pretty (but I'm sure no less prettier than duct tape wrapped around you) but it is supposed to lift and hold, which is what we need.
I know that it has really good reviews in the UK and a couple of friends of friends have them and rave about how good and comfortable they are. I know that they sell them in the USA too, so i've put some links below for you ladies to have a look at.
This is the main Faveo website, they show you a demonstration and if you click on the 'Buy' tab it gives you a list of retailers
This is a company that sells them (make sure you choose the correct country)
Let me know how you get on, or if anybody has actually used these bras it would be great if you could share your views.