Thanks for your input mgcsinc.
Yes indeed. drowelf got an L fare on a Sunday, and upgraded at 96 hrs. I am assuming he was speaking about just the IAH-DEN leg.
However, I have not seen any L fares showing up for sale for the Dreamliner IAH-DEN. I do not think UA has any trouble filling this aircraft.
Do you mean you haven't seen L inventory available, or that you haven't seen L fares published for that origin/destination pair?