Most of the time, I pre-order games that I will be playing on day one or have nice pre-order bonuses. If it's a Collector's Edition that I want, then there's no easier way to get it unless I pre-order it so I always do so.
I have Halo 4 and Forza Horizons pre-ordered. Going to be an awesome few months there ;D
I only pre-order games I really really want, and am willing to pay the $110 cost... Yes, games cost $110 brand new here... it sucks
The only games I have ever per-ordered are Fallout 3 and Fallout: New Vegas. I am a huge Fallout fan and will probably per-order any future Fallout games so long as they are not a MMORPG.