Yes, Yosemite might be packed but you are so close!!
Day trips are cool, like what Not Afraid said. All of the places she mentioned would be nice and if you aren't driving all of the way {like we have to from here} you might be more able to tolerate the masses.
Monterey might not be too far, as well as San Jose and the Winchester House.
Of course, I don't drive, I just make the plans so I might be way off on the mileage.
I hope you have a nice hotel. The last time we stayed at the Best Western Garden Court Inn {something like that} and at 2 a.m. we had some seedy looking people pounding at our door.
And it wasn't Anne whatever he name is {Ellen Degeneres' ex}.
Now, when we do stay, we stay more in the city area and not right off the freeway.
Oh, and yes, they have a Target! Air conditioned!!!
Have fun!