My ex-BJJ coach knew a guy who trained around the Chicago area named Jim Valco, and he's one of the best Jiu-Jitsu practitioners around the area without question. He's I believe a brown belt under Eduardo de Lima who runs Gracie Barra Tampa and he won NAGA's superfight championship last year in Minneapolis. He's a ridiculously skilled ground technician and from what I hear, he's a great coach with reasonable prices.
But seeing as how I train at Gracie Barra Bloomington IL, I would also reccommend training at Gracie Barra Chicago, run by Adam and Eddie Redzovic, brothers who are brown and black belts respectively under Carlos Gracie Jr. himself.
MMA schools are cool, but to me I just think it's better to train with the best people in their martial arts and then mix it all you know. Rather than training MMA as a style, learn BJJ, wrestling, muay thai, whatever....all from the best guys at each style and then you will be at another level altogether.
Abashed the Devil stood and felt how awful goodness is...