I go to the $75 MTT buy-in religously, that's where I learned I have so many holes in my game. You read about concepts in books or in articles, but the higher limit areas you actually see them in action!
I observe how often they play in pots at which position. I try to observe which playing styles the players are using. I also try to notice when the game changes from TAG to blind/ante stealing and how often they steal.
I also notice how they play the bubble and final tables.
Wealth of information on the upper limit tables. This is like seeing it all come together. Some of these players make bank playing these MTT's. If they can do it, so can I. I just gotta learn how.
I usally go the MTT leaderboard to find a specimen to follow around. If you are going to learn, might as well be from the best.