At the suggestion of a friend, we recently bought Max, a cooperative board game. We opened it up on Sunday and Taipan loves it. He's asked to play it the past two mornings before I go to my office to work.
We don't play all of the rules exactly as they're written, but we abide by the general spirit of the game. I highly recommend it.
I need some ideas though of how to include the baby, but not let her destroy the game. It's hard if only one parent is around and Taipan wants to do a board game because Taisim wants to be up there too of course, and she has a very different idea of how to play than Taipan does.