Was on UA34 from IAH to LHR a couple of days ago. Full in business first and about 60 people in the back on a PMCO 777. Overall about 35% pax load. I used a GPU to upgrade on a W fare when I booked about three weeks ago, and same on the return. Total fare about $1100 R/Trip from MCO.
I am sure that lower fares would fill up the plane, but oh well.