I actually think PSG would be the perfect job for him. He's excellent in cup competitions and the French league is a competition they should win even if they decided to go the whole season without a manager. What they need is someone who can organize the side (not many managers who are better at sorting out the defensive side of things), bring in a few good players (they have the money to do that, Rafa has the contacts and the reputation to bring in top players), and come in with champions league experience to help them progress as far as possible in the competition.
Napoli is a much harder job. The team is pretty much set up (in terms of personnel at least) to play a certain way. They dont have the financial capabilities or the reputation to attract the big players he'll want, and the last time he was in Italy it didn't go too well for him. Yes they are in the Champions league, but I dont think they'll expect or have what it takes to even get past the group stages.