Yes, I am backing up my iDevices to iCloud. There is a small database for each of most of the apps. I have a number of PDFs in GoodReader which get backed up and that takes half a MB. The Keynote presentations are hefty too. But it was the Camera Roll on each iDevice that caused the problems. I have cleaned them out and I'm back down to less than 2 GB used now out of the 5 GB free limit. Should be able to go for a very long time without bumping the 5 GB limit again now.

The advantage of backing the databases up to iCloud is that if I lose an iDevice on the road I can buy a new one, then restore the apps from iTunes and restore the databases from iCloud. I just won't have my music and photos until I get home again, but that's no big deal.