I think some of the replies may be leading the OP astray.

While it's true that there are large Chinese communities (with great restaurants and shopping) in the suburbs, for a tourist coming to Toronto, the first Chinatown to visit is definitely the "original" one centered at Dundas and Spadina. It the only one (other than the smaller pocket at Broadview and Gerrard) that it truly "urban", where one can walk around rather than having to drive from location to location.

Although I do agree with Rejuvenated in that the downtown Chinatowns have become much more mixed, with large Vietnamese and other Asian influxes. But that's not to say that there aren't still some great Chinese places remaining.