Everything you ever wanted to know about Lake Berryessa is available at my web site: http://www.LakeBerryessaNews.com. Also check the Lake Berryessa News Facebook page regularly.
On my web site you'll find a downloadable detailed map of the area with all the activities available and the contact info. Primitive camping available at several resorts. RV camping too. Also two resorts rent cabins: Markley and Pleasure Cove.
I have links to several other sites that give info on hiking and other activities.
Have fun.
Peter