Traditionally, I've preferred to use my miles for upgrades on international flights. My pet peeve in that regard is being forced to buy a higher-priced fare class just to have a chance of getting an upgrade. If the higher price is required, then the upgrade needs to be confirmed immediately.

Lately, due to financial circumstances, I've been using awards for domestic travel on trips I couldn't avoid. As far as those go, a pox on airlines without one-way awards.