This is a great forum.
Let's say I am 50-100 BB ahead mid way in a tourn
Should I lay low and let the short stacks fight against themselves and the increasing blinds?
Should I play a regular cash post flop game, calling to see the flop. I know I will be HU with a shorter stack who may push shove on the flop or turn?
Should I play the aggressive pre flop game and fold to a reraise?
You can wait for good
hands if you want; your stack size gives you that luxury. But a good use of the big stack is to apply massive pressure to mid-size stacks.
Let's say you have 100BB and the other players at the table have between 10 and 80n BB-- a player raises and it folds to you.
Short stacks are getting desperate for a double up and will call a raise (if they haven't shoved already) with any hand they'll raise with, so you'd need a good hand to get involved here.
If the raise came from another big stack, he might be stealing, but you're putting nearly all your chips at risk to find out. You really need a good hand or a hand that gets good implied
odds to tangle with another big stack.
But if a mid-stack player with 20BB raised to 3BB, what can he do if you repop to 10BB? He can really only fold or shove for his tournament life. What you need to do as a profitable MTT player is identify the mid-stacks who raise quite wide, but will only go all-in for their best hands. In this sweet scenario you can steal with ATC.
In the case where it gets folded to you and there are only midstacks behind you to act, you can often grab the blinds&antes with a raise. Be careful of doing this with short- or big-stacks behind for the same reasons mentioned before.
These is are somewhat idealised situations, and you need to be continuously analaysing the table to find those spots where you can steal or resteal without seeing a flop.
You'll notice that the conversation thus far implies that your position and the relative stack sizes are more important than the cards you're dealt; a big deviation from cash game situations.