For the campaign I run, I go with a Jedi-like concept for PC's. I think in 4e PC's are radically different than normal NPC's and monsters (they have healing surges, they have healing powers, they have daily powers, and even for martial characters there is stuff that's half way "magical"), and I like to have an in game explanation for this. They wield a force that few others can tap into (in SW it would be "the force", I call it "destiny", in another campaign world it might have a different name). I have an order for them, again much like the Jedi order, and have schools/towers (somewhat like Hogwarts), this gives a uniform front, and allows me to explain multiple adventuring groups, encourages a certain code of ethics, etc. It also sets a nice platform for the occasional visiting player. And it was very easy for me to create a Sith-like organization as the antagonists. If I ever have a TPK or near TPK, it wouldn't be too difficult for another group to be briefed on the current plot by the order, and pick up where the deceased PC's left off.
