The Fray Marcos is THE hotel in Williams if you are taking a trip on the Grand Canyon Railway. Their rooms and restaurant are included in promotional packages offered by the Railway, and the hotel is located right next to the depot.
It is a nice family hotel. The rooms are good-sized and they have an indoor swimming pool and spa. The pool is always cold and the spa is always foamy, but the kids enjoy it. I would compare it to a Ramada or Holiday Inn... nothing fancy, but it is clean and comfortable.
Your package there will most likely include meals at Max and Erma's buffet. The food there is horrible, the service is great and you can't beat the convenience.