App data - keeping it safe

I have an iPhone and iPad syncing with a huge Win7 iTune library.

I need to change to sync with iTunes on my Mac. I don't really mind losing anything but the application data on the devices. I don't see a way to keep my app data.

It is pretty easy to keep all my music, movies, and apps. But I am struggling with the app data part. Any thoughts? I actually went through the Map bookmarks and emailed them, but there are so many things in the various apps that I depend on...