I have finally 100% Super Mario Galaxy with Luigi.  About time, it took me 20 months to beat it.  Ok, I guess I didn't try to beat it on all days.
After watching the Mario Marathon for charity, I wanted to finish this game.  When I booted up the game today, I seen I had 90 Stars with Luigi so I was like "Hey, I could beat this today."  I'm really glad I did to.  I always wanted to 100% this game and I finally have.  Once you get all 120 Stars and beat Bowser with Luigi, you get "Grand Finale Galaxy."  What the Grand Finale Galaxy is the very beginning of the game, the Star Festival.  Once you beat Grand Finale Galaxy with both Mario and Luigi, you get special pictures sent to your Wii Message Board (see below), and special letter to the Wii Message Board (see below) and you get to see your death count with both characters (Mario: 141  Luigi: 86).  Also, your game file is all sparkly.  What's next?  Super Mario Galaxy 2.  I am super excited for it and I can't wait till it comes out.  I'm curious how much harder the game is going to be compared to the first one.  Here are a few pictures I took with my camera.  P.S.  I guess we have to make a character page for Bill Board now.  :-P