If you go just over the River, some options might be:
Bin 36 - Dearborn and Kinzie
Paris Club/Hub 51 - Hubbard west of Dearborn - neither of them is outstanding but both have crowd-pleasing menus
Smith & Wollensky - State & the river: steak steak steak
Harry Caray's - more caz- Italian steakhouse
Other options in the Loop:
State & Lake - tavern-like place in the WIT. Haven't been there myself.
Elephant & Castle - chain; not super-fancy; nothing will surprise you here.
Miller's Pub - Chicago landmark - I hear the ribs are outstanding (not a pork-eater myself)- a little further south but a very quick cab ride or nice walk at Wabash near Adams.
"You should eat!"