Road trip from NYC to Canada
 

I'm from California and planning a vacation in both NYC (Niagra falls) and Canada. First timers for our group (older parents and 3 small kids + 1 teen boy). What do you suggest in terms of itinerary, places to explore, we like history as well as popular attractions. Places to stay.
thinking summer this year or Fall. We don't have a budget yet and we have 7 days total including traveling from/to CA.

I see you've tagged British Columbia, Newfoundland, Ontario, and Quebec in your post. You've also listed NYC (presume you mean New York City) and Niagra Falls. That's some huge total territory; given that you only have 7 days including travel to/from California, you're going to do well just to visit NYC and Niagra Falls. So, travel to/from CA = 2 days; travel from NYC to Niagra Falls, maybe 7-8 hours. B.C. is of course completely out of the equation. How much time in NYC? Or, if you just want the Canada side, maybe fly into Buffalo or Toronto?

It's Niagara Falls, which is not in New York City.
Where exactly are you planning to travel? If NYC and NF are musts, you have no time for anyplace else.

Mainly Niagara Falls, been to New York in the past (2 times) and have done some of the tourist attractions (timesquare, central park, statue of liberty, etc.) already, so this time, we would like to see Niagara Falls (thought it was on New York's side?). Since Canada is close by, we want to make a trip out of it too. We want to see visit Toronto and Quebec but recently found out that they are about 5 hours apart (driving), so not sure now. Never been to either place, so don't care which one to visit first, but definitely, want to make a convenient trip so that we don't lose time driving.
Would you recommend flying to NYC or fly directly to Canada? If Niagara Falls is so big that we can see it on the Canada side too, then perhaps we should fly to Canada and spend time there instead?

New York STATE is huge. NYC is New York City and is not at all close to Niagara Falls, which is on the USA/CANADA border. You need to decide what you actually want to see in Canada, and consult a map.

There is Niagara Falls, New York and Niagara Falls, Ontario. The Canadian side has the better views, most of the attractions and 14,000 hotel rooms to choose from.
Niagara Falls is 7-8 hours drive from New York City and 2 hours from Toronto. The closest airport to NF is Buffalo,NY, about 45 minutes away.
Everyone 16 and older requires a passport to cross the border. Those younger require birth certificates.

From Toronto to the province of Quebec border is about a 5 hour drive, Toronto to Quebec CITY is about a 10 hour drive, both times assume no stops.

Second the suggestion to consult a map.

Would you suggest flying to Quebec City from Toronto to save time? What are there to do in Quebec and Toronto in terms of the major attractions and must do's?

See if this works for you: Fly to Buffalo NY. Get a tour from Buffalo to Niagara Falls. After you have seen the falls from both sides, take the Amtrak Maple Leaf to Toronto.
Near the train station is the CN tower and the stadium where the Blue Jays play. The hockey Hall of Fame is also worth seeing.
Leave Toronto on a ViaRail train for Ottawa, Quebec City or Montreal.
There is an Amtrak train that goes from Montreal south to New York City through Albany and down the Hudson River.
I always advise against taking a rental car either way across the border.

You need 2-3 days in Niagara Falls (both sides) and the same in Toronto. Not nearly enough time to go anywhere else.
Fly into Buffalo and out of Toronto. Lots of bus and train options between NF and Toronto.

I don't think you really need 2 to 3 days in Niagara Falls. It could be done pretty thoroughly in one full day. On the American side, I suggest walking to Goat Island for the best views. Also, Maid of the Mist and the Cave of the Winds. That being said, with seven days, I might limit myself to the Western NY and Southern Ontario area. With your limited time, I would fly into Buffalo and rent a car. I think a Niagara Falls/Niagara on the Lake/Toronto trip would work with the time you have.

Any city can be done in a day if you only want to do one days worth of things. There are the 2 major attractions on the U.S. side of Niagara Falls, and dozens on the Canadian side, many of which will be very attractive to the children and teen. One day would skim the surface.

What do you consider major attractions? I can't think of "dozens" of major attractions on the Canadian side. But I guess if they are traveling with kids, the carnival that is Clifton Hill might be enjoyable.

Can we get real here? There is exactly ONE major attraction in Niagara Falls and all the things/views like the gorge, etc., directly associated with them and everybody knows that. I am sorry but the Waffle House, that "observation tower" and those hotels with martini glass-shaped bathtubs are NOT "major" attractions.

There’s a wax museum.

Fully agree, one main attraction - the falls.You nan find museums, etc anywhere.
If you like history, drive to Boston and have a Tea Party. Plenty of history in and around Boston.

So only natural phenomenons can be major attractions. I guess Toronto, NYC and even Boston have nothing to offer then.

Yes and I think tis is too bad that there are so many attractions at the Canadian side of the Niagara Falls. There is this beautiful nature spectacle and then there is kind of an amusement park.
But I agree to the other posts, look at a map and check the distances. For 7 days it's way too much in my opinion!

And the Mystic Maze of Mirrors.

And "believe it or not".... a Ripley's