I know that I can look at maps etc. but advice from those of you have done it please. Best route from NY to Niagara AND similar from Niagara to Ottawa AND Ottawa to Boston. We want to do each drive in only one day as time is limited. Help with times and stopping places please? Thanks

Best suggestion is to get maps and a 'triptik" from the AAA - will give you all the best routes, sites, stops, etc.

First of all, Harry is, if I read his email address right, not in the US, so the autoclub he'd go to would not be AAA. Second, AAA isn't all that helpful retops and sights -- you just get a tourbook. And then, in an effort to be more helpful than simply saying go get maps, I'd ask first what time of year you are talking about.
Anytime after about mid-October to mid-April you risk anything from snow-squalls to blizzards on the NY-Niagara route. Because they are north of the lakes, traveling through Ontario is less dicey.

From NY to Buffalo/Niagara, the as-the-crow-flys route (I-87 to I-84 to NY-17 to I-384 to I-90) is scenic but slow in places and can be winding in ways that don't show up on a map. You'll see a lot of small-town America and some pretty hills and lakes, but I'm not sure (a native who does it often should tell us) if it's any quicker that the right-angle route entirely by Interstate (I-87 to I-90/Albany to Buffalo), even though the mileage may be much longer by Interstate. I'm guessing the time by Interstate would be a longish day -- maybe 8+ hours, but someone who's made the trip recently is a better judge. And that's in good weather. The hills/"mountains" over the "crow-flies" route can get socked in by fog or small squalls, but I-90 west of Albany can be a nightmare in a blizzard, of which there are many due to the lake effect.

From Niagara to Ottawa, definitely stay in Ontario (shorter, much less weather). From Ottawa to Boston, go through Montreal (actually if you have the choice, spend your time in Montreal instead of Ottawa) and Magog to connect with I-91 south. (I-87 takes you back to Albany and unnecessarily out of your way. Also, I-91 is very pretty.)

Many thanks for your reply. Most helpful. We are travelling first week in October so hopefully weather will be OK. Yes I am from London not the US but I did get TripTiks!(don't ask how) The maps are not the easiest to read however, with your help I think we will manage and have a terrific time. thanks again.

New York City to Niagara Falls, either NF new York, or NF Canada, is a long drive. Take the New York Thruway, which runs north from New York City, to Albany, and then turns west toward Buffalo.
Once you get near Buffalo, the road gets very confusing, andyou should look for signs that say Canada, and follow them to Niagara Falls Canada. This takes you through Niagara Falls, NY, anyway. Allow the better part of a day for this trip. 9-5, more or less.
Once you get into Canada, it's worth slowing down and going to Niagara on the Lake, on your way towards Toronto.

Once you've seen Niagara on the Lake, take the Queen Elizabeth Highway toward Toronto.

If you are going to stop in Toronto, stay on teh Queen Elizabeth untilit changes its name to Gardnier Expressway, and you are in downtown Toronto.
If you are not going to stop in Toronto (and it's worth a visit) stay on the Queen Elizabeth Highway until you come to the Ford car and truck plant in Oakville, and then move to the right lane and follow the signs for highway 403. Highway 403 takes you north east, to Highway 401, which runs east across the middle of Toronto.
Stay on Highway 401 as you drive east from Toronto, until you come to highway 16, which is east of Brockville. Take highway 16 north to Ottawa.

This is the quickest way to Ottawa, but not the most interesting. It will take about 5 hours after you get on Highway 401 in Toronto, and about 6.5 if you start from Niagara Falls.

For a somewhat more inteesting route, turn north on Highway 15 just past Kingston, and go north to highway 7, and then take highway 7 into Ottawa. This will add about 30-45 minutes to your trip, but you'll go through Ontario vacation country.
To take a full day from Toronto to Ottawa, take highway 401 east to Port Hope. Go into Port Hope, and then take Highway 2 to Cobourg. Back to 401 until you get to Trenton. Then head south and cross into Prince Edward County, south of Belleville. Drive through the farmland to Glenora, and take the ferry boat to BAth, and then follow the shoreline of Lake Ontario into Kingston. Visit downtown Kingston, consider visiting the prison museum if you like this sort of stuff, and Fort Henry, which is on the east side of town. From Fort Henry, follow highway 15 north through Smiths Falls to Highway 7, and into Ottawa.
There is no easy way from Ottawa to Boston, because there are the Adirondack Mountains in the way. I'd probably go north-east to Montreal, and then turn south and take Quebec highways south to meet Interstate 89 to Boston.
BAK