Buddhas and canons on display in the Kampaeng Phet National Museum
The Kampaeng Phet branch of the National Museum is a rather typical example of provincial museums. There are a lot of glass display cases full of old artifacts. A few of the key displays, such as the Shiva statue, are duplicated in the information center at Aranyik, which I would say is a much better experience.
Next to the National Museum is the Provincial Museum, housed in several wooden traditional Thai styled houses. Unfortunately the museum didn't appear to be open on either of the occasions I tried to visit, and no hours are posted. You can easily have a look around the outside of the buildings but I don't know if there's anything inside to see.