take the ferry ride.. then you don't need canada visa to be on the foot of the fall, which is what you would see from Canadian side anyway. If you want to visit Montreal, then consider visa, otherwise, US side is fine.

on way, you might want to stop at woodstock, just for pictures.

Nothing much to see along the way.

Alternately, you could drive across maryland to Pittsburgh, and head up to Niagara, (about 9 hours drive from DC). That would be more fun. While in Pittsburgh, go to Metropol, west of Pittsburgh, and also to another bar near Univ of Pittsburgh. This one used to serve unlimited Rolling Rock for a 5$ entry back in early 90s.

_X