In Williams we stay at the Grand Canyon Railway RV park. Its next to the grand canyon railroad depot and hotel. RV guests can use the hotels indoor pool.
Around Williams there are 3 KOA's. We prefer the Circle Pines KOA over the others as its the only one thats wooded. There are a few other RV parks as well but GC Railway RV is by far the nicest. Even has an onsite kennel if you have pets you want to leave for the day while out and about.