In the late 80's and early nineties I got terribly spoiled, had Pan Am Platinum and never flew in the back of the plane. I dreaded sitting in the back...

Well., PA went bust, my life changed in other ways... although I kept flying, my loyalties were split among a bunch of different carriers and I never went above mid-elite on any one carrier at a time.

Now I'm top in three, but realize that it could all change again. Therfore I make sure that I've got enough miles in reserve at all times to last me at least through 3-5 years of my needs in order to be ready for any contingency (that's how much I hate the back of the plane!)