I agree with the comments on DFW-LAS. I never upgrade that because to me it's a waste of stickers. Ironically, just today I was on one of the many seriously delayed flights out of DFW and kicking myself for not springing for the upgrade, but it's not like you can predict these things. I ended up getting off the plane anyway, so it was moot (I guess if I had sat there for 4 hours in F in the comfy seats and then gotten off the plane before it pushed back, I'd have gotten the stickers back? Hmmm)

However, my angst over the DFW-LAS mileage is offset by the 987 miles for DFW-DTW, which was my shuttle for much of the past year. I blew plenty of stickers on that one.