You can backup whatever you like. Mybackup Root will give you some defined options to backup stuff. Its very cut and dry with Mybackup Root.
Titanium Backup you can get more selective as to exactly what you want to do. You mentioned Angry Birds, you can select Angry Birds from the list it compiles of all your apps and do a backup then restore it once your situated on a ROM.
Thanks. I wasn't sure if there was something that I should backup that wasn't obvious. Is one of those better than the other or is it one of those "pick the one you like" deals?