Where to travel

I'm planning a trip for my anniversary. We were suppose to go to Chicago but decided to stay in Canada. I'm looking for suggestions on where to go. We do Toronto and Niagara Falls all the time so we're looking to stay away from them. We're going for 4 days in June. Our budget including hotel and transportation is 1,300 2,000 for both of us. The main thing is we do not drive so the city we go to must be a major city that either has an airport or VIA rail station.

We will be traveling from GTA.