What is it you don't like about the 17-55 for weddings etc? Is it just the reach or the quality of the shots? I honestly think (keep in mind i'm no pro) the 17-55 plus the 85 are great for weddings. The 70-200 would complement the 17-55 but by the wording it sounds like you're looking for a replacement? You won't often find much use for telephoto at a wedding though, especially if you're inside in a church and are the main photographer (right in the action).

I've got the 24-70 2.8 and the 70-200 2.8 non IS and I've done a few events and honestly I kept the 24-70 on my camera the vast majority of the time, the 70-200 was only for portraits at the end of the day etc and even then was used very sparingly