Hi. I need help with an initerary. This trip is for 2 young people.

Lax - JFK (spend 3 full days)

JFK - Washington DC (by Amtrak and spend 2 full days)

Washington DC - BUF or YYZ (spend 2.5 days) we'd like to visit Niagra Fall and Toronto city. What are the interesting places? (We're interested in museums, historical places, food) Or should I skip Toronto? Spend 2d1n in Niagrafall and give NY or DC an extra day to stay? Thank you