I think Paul George flows slightly better but it would depend a bit on the first name and surname. I wouldn't put George last if my surname began with a J sound.
My DS2 has John George as middle names and I've only just this minute registered the possible Beatles connection (although I did quite like George Harrison) - to us they were mainly family names. I don't think people will immediately think of it with two such classic names as Paul and George - they might if you picked two names of people from a band that were quite unusual names in themselves, like, say Axl and Slash!
The "George Paul" order makes it a little less obvious as I usually think of the Beatles as John, Paul, George and Ringo in that order. But "George Paul" when said aloud seems to sound like the more famous "X Paul" name, as in Pope John Paul. Every second boy of the generation now late-30s in Ireland is called John Paul. So GP, more removed from Beatles but close to famous Pope.