From the NFTA Terminal around one mile east of the Rainbow Bridge (a dodgy area, especially at night), bus 40 goes to Buffalo ($2.65, one hour).
A couple of miles northest of central Niagara Falls, with Empire and Maple Leaf service to NYC and Toronto.
About 10 miles east of downtown, this is a regional hub.
The downtown Amtrak train station is served by the Empire (NYC to Niagara Falls) and Maple Leaf (NYC to Toronto) services.
The hub for Niagara Falls Transportation Authority services, as well as Greyhound buses.
The Niagara Frontier Transportation Authority serves the greater Buffalo and Niagara region.
Greyhound's drop-off point in Niagara Falls is the Quality Inn & Suites.
Due east of downtown Buffalo, this Amtrak station is served by Empire (NYC to Niagara Falls), Maple Leaf (to Toronto) and Lakeshore Limited (to Chicago) trains.