I vote with "Wiggums" RENT A CAR Changing trains is a hastle unless you have a lot of experience. The trip takes 4 hours from when you can start which may mean a few hour wait at FRA or Frankfurt Main Station. Renting a car takes 10 to 15 minutes and I have driven many times from the Frankfurt airport to Nuremberg and to Weiden (1 hr beyond). It is an easy drive. Most arrival are early in the morning so you are fairly fresh and the day is bright so it is not a problem to drive. The train would be ok if you were going to a distant main city, but to smaller cities it is a hastle.