On my 4 year old S P85, we had the factory film in a few places. Elsewhere, the paint has held up very well without any other protections.
For our new S 100D, we're not currently planning to do anything.
Our S P85 didn't have extra tinting installed for the windows or sunroof - which hasn't been a problem after 4 Texas summers - and we don't plan to do any tinting on the new car.