I'm just using icloud. I have my 4s, ipad2, and iMac all set up on it. Anything I do on my phone instantly goes to the other 2 devices. Typically save the pics on the computer and delete from my phone. Don't have much music on the 4s, I have the Aol radio app for music. Have videos and movies on my iPad and iPod. So don't put those on my phone either.
So far I have 2.6 gigs used on my iPhone, that's it. And most of that is apps