My account hit 350k at one point before buying the parents-in-law RT tickets to NZ, earning some more, and then sending my family to OSL on miles killed that (took it down to about 20k). Now with spend and travel its back up in the 225k range.
I also sent my wife and I to NZ way back in 2005 in C (on Air New Zealand), which killed what had been a mostly credit-card-miles pile.
I used to never spend miles on anything other than upgrades (or more accurately, upgrade attempts) on int'l flights untile those big trips above.