Pizzeria Uno is closer to your hotel and one of my stand-bys. Also nearby is Lou Malnati's on Wells.

http://www.unos.com/
http://www.loumalnatis.com/Locations/

Second the recommendation for Xoco!

For a local chain with good (if not good for you) food. There is a Portillo's not too far away as well. You can try a Chicago-style hotdog or a Maxwell Street Polish.

http://www.portillos.com/portillos/locations/