Quoted from vid1900:Space Shuttle would be an amazing game that you can usually get multiball every time.
My seven year old gets multiball with some regularity on our Space Shuttle. He loves it. It's a great game for casual players and still pretty fun for more skilled folks. I was able to teach my son how to really play pinball in a single day. Went from constant double flipping to surprisingly decent ball saves and aimed shots in just a few plays.
The on field locks are fun to hit and easy to see and since they're left between players are usually available for multi-ball.
EDIT: If you don't know, the locks are always lit, and after collected, any center ramp shot starts multi-ball: Can be two or three balls depending.
EDIT 2: The auto link is hitting the wrong page. We're of course talking about the Williams game.