I dont play these very large tournaments all that often, but when I do, I make no strategic adjustments at all. Its still just tournament poker with the only difference being, you are very unlikely to reach the final table, and if you do, you need to have the time and stamina to play for 10 hours. I ran deep in a 2$ "big" on Stars recently. This had a little over 1.000 people playing, and was already an 8+ hour event, when I busted out in 4. place. By the way Stars slow the blinds in these "big" tournaments, when you get to the final table. Rather than 10 minutes, it is now 15 minutes between blinds going up, which obviously drag out final table play for better or worse.