I agree with the suggestion for Richtree (formerly Le Marche) in BCE Place, which is across Hummingbird Theatre. There is a lot of variety so it's easy for everyone to find something they will like.
Up the street on the east side of Yonge is the Irish Embassy Pub
(www.irishembassypub.com) which can be a lot of fun in the evening.
Behind the Hummingbird, on the Esplanade, is the Esplanade Bier Markt (
www.thebiermarkt.com) which is very popular with the afterwork and weekend crowd. Very diverse beer menu, featuring some unique and less common beers from around the world.
Along is Church Street, south of Front, are a number of restaurants including: a French restaurant called Le Papillon (
www.lepapillon.ca), and the Keg Steakhouse.
You can also wander eastward along Wellington, which is just north of Front Street, to check out some of the restaurants there.
There are lots of restaurants to choose from, depending on your preferred cuisine and budget.