What iOS version are you running? I was having this problem on my 4S and iPad Mini, each taking up a gig of space. No camera roll. This was on 6.0. I think it had something to do with SMS/iMessage history not wiping properly and the only way to fix it was wipe the iOS device and start new.
But either 6.1, 6.1.1, or 6.1.2, not sure which one, fixed this problem, and my iCloud backups are now at manageable sizes. They both total now a gig in size, which is where I think it should be.