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As it stands, your proposed trip is certainly doable, but I prefer to think in terms of days spent doing and seeing things rather than nights. For example, you list Boston as two nights, but in reality you only have one day to see that incredibly vibrant and historically rich city since the first night will be spent getting over jet lag and on the morning of the second night you'll have to hit the road for Niagara. So try to think of it more in those terms to get a better idea of what you'll be able to do.

The drive from Boston to Niagara can be quite enjoyable in its own right, so don't be in a great hurry to just get from one destination to another. Take some time along the way to see something more of North America than the big cities. The Berkshires in western Massachusetts are the only 'mountains' you'll be driving through, although the are pretty old and worn down. And between Toronto and Detroit you might want to take some extra time to drop south and follow the shore of Lake Erie rather than just take the motorway.

AZBuck