Pizano's is a great pizza place just off of Michigan avenue on Dearborn and Delaware. (much better than Giordano's and is a relative of Lou Malnati's - less touristy, and great pizza!)
Avec is a very cool restaurant in the west loop on Randolph - great food, cool atmosphere - no reservations taken.
Definitely do an architectural cruise. Chicagoline Cruise is another great option http://www.chicagoline.com/