Like luvgirlfites, my first preference is topless with thongs. I too, like to see the big, soft boobs mashed together, and as an additional tease, I prefer the women to remove their own tops just prior to the match -- like they're ready to get down.
A close second, however, is a one piece swimsuit. I recently purchased an old Ladyhawke match between BBW Dawn and a rather "thick" Christy. Both women wear a one piece suit, but it actually complements the whole match. Strange as it may seem, it's like someting being left to the imagination can make the match more exciting.
Lastly, I find total nudity a distraction. LOL