I would have to reccommend something along the lines of a backplate and wing. I personally have not gone that route all the way, the unpadded harness looked too rough. Luckily for me, someone at my LDS recommended Dive Rite's TransPlate (make sure you read that Plate, not PacII). Although there is a backplate(which I thought would be very uncomfortable), I find that I honestly can't feel it. The benefits are many, the one I like the best is that my tank feels very secure, both on land and in the water (the double tank straps probably don't hurt either!). I, like many women on this board am very well endowed in the chest area. This has made finding a BC that fit across the chest a big challege (no pun intended). The harness of the TransPlate is so adjustable that the size S can go from a larger person right down to one who is quite petite. I liked it because the chest strap sat above my chest and yet didn't it look like it was sticking out more than it already did.
Some people have said that because it is a back inflate it will push you forward so that you are always horizontal. I have found this to be the case only once. That time I was at the surface, it was very choppy and so I thought to myself, "Self, try adding some more air to see if you can float higher out of the water so that you can breathe without the regulator (remember we were on the surface!)." In that instance only did I ever feel like I was being pushed forward, and mind you, this was when the RecWing (55#) was almost fully inflated. All other times on the surface I have been very comfortable maintaining a vertical position or, if wanted, laid back. Under the water, I am able to achieve any positioning I want: horizontal, vertical, inverted, on my side..etc.
Well, that was a bit more long winded that I had originally intended but I think it got my point across: try the Dive Rite TransPlate. If anyone has any questions, feel free to PM me.