Fun little new "enhancement" I discovered this evening trying to book flights to Hawaii this fall. The availability of upgrade space changes based on routing. While this is nothing new for other revenue fare codes, I've never seen it before for upgrade space. Behold this new "feature" in action with the example of UA 785 on October 5th. This appears to be a relatively benign 757 from LAX->LIH, but choose the incorrect routing and you'll get to sit in economy! If you are lucky enough to live in LAX, there's R4 for you. However if you commit the faux pas of coming direct from IAD to LAX, no seat for you! If you add a stop in DEN, you could get R3 or R1 (depends on your IAD to DEN flight). Going through IAH nets you R2 (and a 3 hour ride on a ERJ145). So, thanks to this delightful new "feature", United gets to fly me to DEN (and waste my 2 hours) for the honor of collecting $7 (which I believe the airport gets anyway). Moral of the story, make sure to check multiple routings when looking for confirmed upgrade space at booking.