Just got back from Budapest traveling with our 12 year old son who isn't really into history, art, etc. Would highly recommend Budapest Retro Museum if you're looking for something different to do with your kids. It's an interactive museum so it's okay to touch stuff. The exhibits were well done and visually appealing. You can be a TV anchor, drive a police car, ride a motorcycle, play a video game, etc.
We all really really enjoyed this museum and felt it was important for our son to see this perspective on Hungarian history. There were several Hungarian families touring too and they seemed to like the museum and when asked, said it took them down memory lane.