Just got back from CA. Up north you should hit the Cal Salmon. It is an understatement to say this is a classic. It doesn't look like much but oh so sweet. Go there if it is around 3000 or higher. There is big water, play and creek boatin' to be done.
On the other hand, If you can pull it off get on the MF Feather, Devil's canyon run. Spend three days in there. This is easily the most speacial place I've ever been in a kayak. 1000 ft vertical CA white granite walls with 100's of cascading waterfalls coming in everywhere. You just pull into the eddy and fill up your water bottle. 34 miles, Tons of rapids, Self support, class V, with one portage. You may choose to portage other stuff. This is the one!