IHZ, if I were visiting similar to what you indicate you'll be doing (or maybe past tense now), I'd be doing the same thing and go to all the great pizzerias in the Chicago area that I went to and loved during my many years of living there in the past. Now I'm far away and only can get there for some great pizzas several times during the summers.
I would definitely put the original Uno's/Due's high on the list (slight preference for Due's). They've went downhill from their glory days of long ago and when I used to frequently dine there before my classes at Loyola Law School a number of blocks away, but if lucky, one can still get a pretty good pizza there. But for years, they were the King of Chicago Style Deep Dish Pizza and it's where it all originated. My advice to all -- stay away completely from the Uno's Chicago Grill where they attempt to clone an extremely poor copy of this style pizza. The current original Uno's/Due's still attempts to duplicate (somewhat) the original great pizza that made them famous.
There is a Pizano's in the downtown area just a block or two from the Grant Park area that is very good. Giordano's is good, too, but their locations throughout the country are good, too, and consistent with that of those in Chicago so you can go to those instead. While Pat's pizza does have deep dish on their menu, they are only good for their ultra thin crust pizza and all I know of never go there for deep dish style. As I wrote in another thread, I suggest one go to Pat's for a small thin crust pizza and walk two blocks down the street and have a small Lou Malnati's pizza (see http://www.pizzamaking.com/forum/index.php/topic,8921.0.html
). And I'm not certain you can get a thin crust pizza as good as Pat's elsewheres, but who knows. And you'll need to check if those locations are open for lunch first.
I noted on a list of places that you may have tried. I would leave Pequod's, Bacino's, and Gino's East off the list, but that just a personal choice. I am unaware, too, of Arnie's. Louisa's, of which I am too very familiar with (ex-Uno's cook), is NOT open for lunch on most days. And I am totally unaware that there is a Papa Del's in the Chicago area.
BTW, where are you flying in from? PM me if you'd like any other thoughts or opinions as I'm always happy to share my experiences with others.
P.S. Suggest you utilize the Chicago Style section more.