4 player with the family is crazy. One player would run way ahead, my niece would not have a clue how to play but just be happy pressing buttons, my sister hasn't played a mario in years, and I am the only one who really got it.
We just played the 'suggested levels' which were a little hard for first timers. It was fun, but the skilled players blew away the none-skilled players.
i just carried my niece around because she would just slow the rest of us down. My niece is 5 so we just give her the controller and she thinks she is playing. She only wants to win, so she doesn't grasp why a challenge is good and thinks it's unfair otherwise, so carrying around the levels was just easier, but whatever it was pretty fun.
4 player really does change the game, up from even 3 or 2 the game just 'feels more crazy'.