This is a great value trip 16-28 April, visiting Lisbon, Toronto, Niagara Falls and New York, flying from Manchester or London (same price).
This is based on Manchester flights.
You'll fly to Lisbon from Manchester and stay for two nights at https://www.tripadvisor.co.uk/Hotel_Review-g189158-d10587959-Reviews-Alfama_Yellow_House-Lisbon_Lisbon_District_Central_Portugal.html
which is in the centre of Lisbon, ideal to access public transport and trains.
You'll fly direct to Toronto, arriving late evening. I've allowed 4 nights in Toronto as it's likely on the first night you'll want to sleep after long haul flying and you'll be tired. You'll have 3 full days to explore the city and the hotel https://www.tripadvisor.co.uk/Hotel_Review-g155019-d186891-Reviews-Courtyard_by_Marriott_Toronto_Downtown-Toronto_Ontario.html
is ideally located for transportation including the HoHo buses.
You can book the Greyhound bus to Niagara Falls which only takes around an hour and half (alternative is to hire a car in Toronto for a one way fee, probably around slightly higher price). You will then stay at https://www.tripadvisor.co.uk/Hotel_Review-g154998-d188225-Reviews-Days_Inn_Niagara_Falls_Near_the_Falls-Niagara_Falls_Ontario.html
for 2 nights, plenty of time to explore
You will fly from Buffalo (Niagara) to New York where you will spend 4 nights exploring the city. You'll stay at the https://www.tripadvisor.co.uk/Hotel_Review-g60763-d113343-Reviews-Marrakech_Hotel-New_York_City_New_York.html
This place is in Manhattan and has overall good reviews, rooms have private bathrooms and it's in a good location. There are better, but you are in NY and I'd suggest saving your money rather than spending on expensive hotels as you are unlikely to be in your room much. On your final day you fly back to Manchester late afternoon, with a short stop in Lisbon.
All the details:
Book multistop flights from Manchester to Lisbon on 16/04/2018, Lisbon to Toronto on 18/04/2018 and New York to Manchester on 28/04/2018. Total price £440.28 book on http://www.opodo.co.uk
Book 2 nights in Lisbon £70 http://www.booking.com
Book 4 nights in Toronto £316 https://www.amoma.com
Book coach Toronto to Niagara £28.80 https://www.greyhound.ca
Book 2 nights in Niagara £69 https://www.booking.com
Book flights Buffalo (Niagara Falls) to NY $177.90/£139.53 http://www.delta.com
(Lots of flight times available)
Book 4 nights in New York £351https://www.booking.com