If you go again, try to stay at the Hotel Germain...
http://germaintoronto.com/en/intro_hotel.asp
Not all that expensive, very central and it's the best hotel in Toronto.
Ignore the rates posted on the website, call them and ask for their special price.
Check out the various neighbourhoods (Toronto is a city of neighbourhoods): The Danforth, Bloor West, the Annex, Queen West, Chinatown, Little Italy, etc.... all have their own flavour and amazing restaurants.
Get out of the core if you can. Places like Marche are nice but are just a nice chain restaurant.
Check out
http://www.torontolife.com/ for a list of very good restaurants. I believe you can even search by price (some of the swanky ones are very pricey but if you are on an expense account by all means indulge at least once).