-> Food. At any event concession stand, you should expect crap food at absurd prices. DLLCC was pretty good and reasonably priced by event-venue standards.
I heard many attendees complaining that "there's nothing in this part of town except McDonald's!" In fact, the Penn-Liberty corridor has lots of interesting, exotic, and cheap places to eat, if you look in the right places and times. I especially enjoyed the gyro shop across Penn (did I just spill a staff secret? Oops...) and the Chinese place further down. If you want something more familiar, try DiBella's and the old standby Chipotle down Market Square.
Not only that, but right down the street from the Double Tree, there was a TGIFridays at the bottom of the Consol Energy Center (which was great to go to on Friday night to watch the game) as well as a lovely pizza place by the name of Pizza Milano's which I hit up constantly for hockey games and I can vouch that the people there are nice and the food is great. You may have to wait some time for your food since it's usually very crowded, but you can always find people to chat with or if you drink, they have 2 bars. And the Mconald's isn't the only thing they have in Market Square. Wendy's, Chipotle, Subway, Primantis, Dunkin Donuts, ect. There was even a Donut shop near Double Tree and a few other places around the hotel to eat, you just have to walk around and look (and if a food map isn't provided by the con, print out a map of marked places before you leave for the con. Although it would be nice, you cannot expect the con to hand everything to you). I ran into a few Subways walking around. And if you drive and aren't paying a butt ton for parking, South Side has good food, including the Haufbrauhaus. I think the thing was that some people complaining didn't want to walk to find food (just like some were complaining that a 12 minute walk from the Double Tree to the DLLCC was too much). .