i would suggest lowering your raise sizing and opening up a lot more hands in position, lowering raise sizing during middle/late stages will save you a lot of $$ in the long run..
But remember you are the big stack, make your opponants fear you, if they are all in with you, its their tournament on the line not yours, use it to your advantage..
i would advocate if you have a big stack nearing the bubble, to play ultra aggressive against most players at your table, as they will be wanting to get into the money.
One thing i will say, if you are acquiring a big stack early on, that is usually a sign of a person who is willing to take huge risks early, which isnt ideal in the long run.
ok to answer some of the quesions in the post
"How can I use my big stack to get even more chips"
yep well, open more pots in middle to late position.
ok say you get dealt k 7 suited in the cutoff seat(one of the dealer button) its folded to you, you should raise here to try and steal the blinds, i would say around 2.5x the bb should do it, so if the blinds are 50 100 you bet 250, to win 250, which is great
odds, you only have to do that once per round for you to maintain your stack... so if you get called so what, the flop comes A45 he checks and you c-bet around half to 2/3 of the pot and you will take the pot then and there a high percentage of the time.
Basically the more chips you have, the more you can loosen your range of opening hands, not to say you should go crazy, if someone reraises you all in and you have 3000 to call with your k7 suited its an easy fold, oh well you lose 250 instead of 300-400 which some bet.
"WHAT TYPE OF BEHAVIOR SHOULD I BE LOOKING FOR AND HOW DO I EXPLOIT IT?"
with a big stack, you want to steadily accumulate chips without going all in too often, which should be your aim most of the way through a long MTT. basically you should be looking for tight passive opponants and stay away from the looser more aggressive opponants if possible. look for the guys with a smaller chip stack and be aggressive, verses those players.
In a tournament time is never on your side, you need to accumulate chips steadily each level to be able to make a run in the late stages of the tournament.