I was there at her last appearance (with BirdCloud, what a group!) and really enjoyed it.
I just went to the Green Bay, WI show Monday night so wont be making my way downtown (a Vanessa Carlton pun, of course) Chicago. I did just randomly check and it appears the show is sold out! Nice!
There were barely 100-150 people I'd guess in Green Bay.
I also see she is playing at SPACE in Evanston, IL. Ive never been, but seating layout looks like something similar to City Winery (cabaret tables, etc) and has standing room only tickets available.