A young friend is flying from WAS to SAN for a wedding. He's never been to California before and is thinking of renting a car in SAN and driving up the coast to SFO spending a week or so.

He is on a rather tight budget; can anyone offer suggestions as to how to book a ticket originating from WAS to SAN and then fly back from SFO to WAS. Does he need to buy 2 one way tickets?
How about car rentals? Are there any car rentals that don't have drop off charges if renting in SAN and dropping off in SFO?

I am sure many FT'ers have done this itinerary, how would you do this? Any suggestions as to ticketing, car rentals, driving itineraries, must sees and restaurants are appreciated.