As for Italian you gave two good options downtown. Old School Institution or New Kid on the Block.
Roma's Cafe - www.romacafe.com
Angelina's Bistro - www.angelinadetroit.com
I can not say I am enthralled with any Seafood downtown, I may be a minority in this opinion but that is mine. Well I would get Seafood at Roma's or Angelina's.
I would mention Roast as a non Italian/Seafood option though. www.roastdetroit.com/
Roast is owned by Iron Chef Micheal Symon and they are the best place in town to eat if you are a carnivore. Tough to get a seat unless you get there around 4pm and aim for the bar.