Tower Park is an excellent suggestion, and they have a full service marina/restaurant/bar, board shop and camp/lessons available on-site. T.P. is a KOA that has gone through a number of recent renovations and is very well taken care of. It's not the most popular area of the Delta, further from the east bay so depending on your time of year and day of the week it can be far less crowded.
http://www.towerparkresort.com/