The Delta has a number of camping areas, and many of them have docks that would allow you to keep the boat in the water. Not in front of your campsite, but at least in the water and ready to go. But then, at most of the lakes the water can be 500 yards from the camping area this time of year.
If you like the KOA style of camping Tower Park Marina is probably the nicest on the Delta. Playgrounds for the kids, lots of trees, etc.
If you prefer the state campground experience then Brannan Island comes to mind.
Here is a website from the Delta chamber of commerece: http://www.californiadelta.org/camping.htm
Bethel Island can be nice, but be careful as you can end up behind 20 minutes worth of 5 MPH zone.
Turner Cut Resort is pretty good. It also happens to be close to my regular hang out spot.
I have heard good things about Orwood and it is close to some great places to ride. It also has one of the best launch ramps that has a reasonable fee.
The great thing about the Delta is that you can usually find some decent water even in some stiff winds and many times the it's all glass.