As has been said before the USA is big and 10-12 days is short
I've done the San-Fran to San Diego (with a detour to Vegas) via the PCH and a tour of Wyoming and Montana among other USA trips, the biggest tip I can give anyone is DO NOT pre book your hotels for each day. The last thing you want to do is miss something just because you HAVE to get to your hotel. We have always gone off our planed route, to see something that was unknown to us before the trip started.
John-S in the reply a few before has it spot on, just wing it.
Our 15 days on the PCH Plan
Fly to San-Fran and stop in a pre-booked hotel for 3 Days
Hire a Car ( our visit list had Hearst Castle, LA, Vegas, Palm Springs (we we did not even get out of the car there and drove on to somewhere different and totally unplanned and unheard of by us or anyone else

) San Diego
The only thing we had to do was be in LA on a set date as I had ticket for Nelly Furtado gig ( this was in 2002)
Get to LA for the flight home.
The 15 Days in Wyoming Plan
Fly to Jackson Hole (have a friend there for first night and longer if required)
Hire Car (we had a provisional list of places to go like Yellowstone, Devils Tower, Mount Rushmore)
Get back to Jackson Hole for the flights home.