For me, it's about a 50-50 mix of long-haul premium cabin and short-haul coach. The coach mix has increased now that we have two kids...first class is sort of lost on them...

I hate spending miles on narrowbody F/C. So for all of my North America or Central America travel, I'd rather spend 25k-35k per ticket and keep more miles for good C/F seats later. If I'm getting a "real" 2 cpm on a short-haul coach ticket, I'll redeem. If I'm in the 1.5 cpm range but the award allows me to select a more optimal flight time or routing, I'll still do it.

I usually redeem on routes that are naturally high priced - that's why using an award sometimes opens up more options than the lowest possible fare. MCI to many Canadian cities via ORD or DEN, for example. Also some Central American destinations, as long as you stay out of peak award demand periods.

Finally, when UA does its periodic 20k R/T sales, I look for an opportunity to book something. MCI-ORD-BDA for 20k R/T - available for five seats on the same flight - was pretty sweet. (Sadly, I don't think ORD-BDA survived long. I never see it anymore.)