I was pretty disappointed with the last level as they were the easiest levels by far, and I was able to get most or all of the coins at the same time.
I'm debating whether or not to even bother getting all the Star Coins. I did for Super Mario 3D Land and it wasn't really worth it. I've seen IGN have a story that shows a different ending or something if you get all the coins. Maybe I'll just watch the video and not spend the time getting the coins.
I also put more time into Nintendo Land last night: playing Pikmin for the first time, the Zelda, archery game and a couple others.
Oh, and there isn't any bots for Luigi's Mansion. The game won't even let 1 player play... Unless I have to use 2 screens to play, in which case the game could have stopped me from playing by myself since I was just using the Game Pad.