I've always used Monoprice screen protectors for my 4S since they are so cheap (60c each). They just came out with them for the 5. Maybe not as glass like of a finish as some of the best screen protectors that are $15/ea., but for the price they are amazing. Good clarity, no orange peel, but not as slick feeling as glass.
I'm waiting for their power cable to come out now. Usually < $5.