Next year will be longer. 2 – 3 weeks as I want to take in Bend, Oregon too. Currently undecided about flying into San Fran and working North and East (through Weaverville) or into Portland and working South(ish) and East.
Lake Tahoe area is supposed to be pretty good.
A friend of a friend that I rode with in Colorado / Utah / Idaho last year resides in San Fran and commented that a lot of the riding in the San Fran area was now very restricted and that it was a breath of fresh air to be able to ride pretty much unrestricted where we were.
When I’m planning a US trip mtbr.com is always a good starter. Use the trail reviews for the areas that you’re going to be and then build up a list of rides that you want to do and work out a plan. Then drop the plan into a post in the respective area on mtbr.com’s forum and you’ll normally get a load of locals come back with comments and advice. You’ll almost always get offers of guided rides.
The other option, which is a little risky but can work well, is to ask in the local shops as soon as you get there. It worked for us in sun Valley, Idaho – but there’s so much riding there it would be difficult for it to not.
Best of luck and have an awesome trip. Anything else that I can help with let me know.