The beginning of the end of the Expo was the move from Ballston to the end of the world. They lost a lot of DC, Arlington, Montgomery County and Alexandria in one swoop. I remember when I could get on the Metro right after work and get to the Expo for several hours before returning. I'd rather have a root canal than have to brave the hours-on-end traffic jams on Route 28 and I-66.
I don't doubt that it's a PITA to get "all the way out" to the Expo Center, but I wouldn't be surprised if >60% of their business (even pre-move) came from people outside the beltway, so it's not like they moved the "DC" expo to Morgantown.
As someone who (rather unwillingly) commutes from Leesburg to Arlington every day (had the house before I had the job - needed to work, can't sell the house), I can say 28's not that bad. 66 can be a nightmare, but for a person with a car, on a weekend, the drive from "DC" (including the inner parts of Arlington) to the Expo Center, it's maybe 30-45 minutes, tops. Given that there is a HUUUUUUUGE outside-the-beltway contingent, is there some reason that we should be asked to make the 1+ hour drive in, vs. the 30-45 minute drive out?
It seems it would make sense to find a weighted-average "middle", so that everyone has to drive an equal amount, taking into consideration the demographics, etc.
This brings something else to mind. I'm going to try to set up a poll....