I have stayed in a few places in Pismo the nicest RV park is
Pismo Coast Village Short walk to the beach,no vehicles around,short bike ride into town or a nice walk.
Pismo North Beach state park is Next to Pismo Coast, all dry camping,short walk to beach kinda seedy at times, some small sites,best look at Google earth to see the sites.
Then there is
Oceano Has hookups and a short walk to beach and the entrance to the
OHV area where you can rent ATVs.
My choice is Pismo Coast Village. If you have Google Earth look at them all and decide.
Good luck and have fun. The Kids will love it on the beach,there are always a lot of sand dollars littering the beach.