What about a western building with interchangeable signs so that it could be changed from one building to another?
It could have signs for a sherriff's office, bank, saloon, drug store, general store, hotel, post office, and restaurant, with these signs perhaps being pieces of card that slide into a holder, rather than permanent stickers, so it could be changed over and over again. In fact each one could have two different sides so they could produce less pieces.
Then it could have a desk, a jail cell wall/bank bars, a bed, a table, four chairs, bar/counter, safe, and a shelving unit. That way by changing around furniture and the sign you could make different things out of it. It would be fun for a kid even if they just had one, but you could also buy multiples and use each one for a different use.
It could also have a small hanging sign to attach to the outside wall which could have changeable inserts making it serve as a wanted poster, an ad for the latest show at the saloon, the day's menu for the restaurant, etc.