If you have yet to book a flight, we recommend Pearson International Airport (code YYZ, Toronto, Ontario, Canada), or Buffalo Niagara International Airport (code BUF, Buffalo, NY, U.S.A.).
If you are flying into Pearson International Airport (Toronto):
To reach downtown Toronto and the Chelsea Hotel, we recommend the UP Express (airport rail link) to Union Station. From Union, take the #1 TTC subway bound for Finch. (This is the Yonge, pronounced "Young", Line, NOT the University Line.) Get off at either Dundas or College station. The Chelsea Hotel is halfway between them on Gerrard Street West. Alternatively, from Union Station, you can also take the #19 Bay Street bus northbound and get off at Elm Street.
If your accommodation is not downtown, the airport is served by Toronto Transit Commission (TTC) buses and other transit systems. Use Google Maps or the airport's Trip Planner https://www.torontopearson.com/en/transportation-and-parking/public-transit-buses. Taxis, limos and ride shares are also available. Some hotels near the airport have shuttles.
If you are flying into Buffalo Niagara International Airport (Buffalo, NY, USA):
There are multiple bus options (FlixBus, Trailways, Greyhound) that cross the border, leaving from either the Buffalo Niagara International Airport or from the Buffalo Metropolitan Transportation Center (bus station, 181 Ellicott St, Buffalo, U.S.) and arriving to the Toronto Union Station Bus Terminal (Canada). FlixBus (https://www.flixbus.ca/ (Canada) or https://www.flixbus.com/ (U.S.)) lists all the buses available from both the airport and the bus station, as well as the prices. FlixBus sells tickets for all companies, or you can purchase from the Trailways (https://trailways.ca/) or Greyhound (https://www.greyhound.com/) websites directly.
(Buses may stop in St Catharines, Mississauga, at Pearson Airport, or even go as far as Scarborough.)
To reach Buffalo’s bus station from the Buffalo airport, take the Niagara Frontier Transportation Authority #24 Genesee bus to the stop "Washington Street South Division Street", which is about a block (3 min. walk) from the bus station.
https://metro.nfta.com/schedules/route/24/timetable
Entering Canada:
For U.S. residents/current or future passport holders who will need to cross the border into Canada, current processing times for U.S. passports are 6~8 weeks for routine processing, and 2~3 weeks for expedited processing, so if you don’t currently have a passport, you’ll want to apply as soon as possible. If your passport is expiring soon, you’ll be permitted to enter and leave Canada provided your passport is still valid on the dates you will be in the country. (Check https://travel.state.gov/content/travel/en/international-travel/International-Travel-Country-Information-Pages/Canada.html for further details and confirmation.)