Frontera Grill is great; it can get very crowded; not sure about reservations.
Think about The Berghoff, a Chicago institution if there ever was one. Very busy, but standard well-prepared food.
For a casual to go while shopping, Gold Coast Dogs for chicago dogs,
Billy Goat Tavern for a gritty atmosphere and cheezborgers.
Harry Careys’ has great steaks and some of the best pork chops I’ve ever had, anywhere.
Russian Tea Time is great for eastern European food, down by the art museum. Try one of their platters. Absolutely outstanding service, great atmosphere, unique food.
Last time I was there a couple months ago, had dinner (business entertainment) at Joe’s Stone Crab, another location of the Miami institution. (I always wanted to go the Miami original and never made it) Stone crab and steak was about $80 per person, plus drinks, but it was excellent.