Meh, I'm actually surprised it took this long to sell out. Like I said, Wilco's gotten a lot of publicity lately, musical and otherwise, so it makes sense. And Conor isn't playing a headlining show in the area, so I'd bet there'll be more than a few people there to see him more than Wilco.
I don't think the venue is too big for them sound-wise. They'll just tailor the setlist to fit the venue, like they tend to do.