First off do not be concerned about not speaking French when you come to Canada. Only Quebec Province has a large French speaking population and most people can communicate in English.
From Niagara Falls, you might consider spending a day at Niagara on the Lake, a nice tourist town that is pleasant to stroll around - maybe take a horse drawn carriage ride. There are hundreds of wineries in the area and many offer tours (free) and tastings (usually a price).
The Welland Canal is about 25 miles away and at Lock 3 is a viewing platform where you can watch the ships go through a lock. Interesting if you have never experienced this.
Continuing on towards Toronto there is a very nice c.g. on Lake Ontario near Hamilton. It is called Fifty Point Conservation Area. The sites are the biggest you will ever see (in the old area) with lots of nice shade trees,
birds galore, nice short walks to a lovely marina, fishing pond, beach.
Prices are $50 for full hook-ups but with your Am. $ that will be about $40 for you.. From there you could do several day trips.
The Royal Botanical Gardens are in the area - a world class facility. You could spend a leisurely day there - restaurants and tea house on premises and a very nice reception building with gift items and art selections.
Also a day in Burlington - visit their art gallery (free admission). A beautiful building to wander around and check out the various guilds and solarium. The Performing Arts Centre has a big variety of live entertainment and theatre productions as well as known entertainers.
There is a nice waterfront area with walks along Lake Ontario and several restaurants.
A day trip to Brantford and history pertaining to Alexander Graham Bell
(telephone). Some lovely walks, gardens and casino in the downtown area.
A day trip to Toronto might be of interest. Take the commuter train into the downtown area if you do not wish to drive (you don't).
Leaving this area, what about heading West to cross back into US at Windsor/Detroit and stopping at the Henry Ford Museum and Village before picking up I-75 and going south to home.
Also between Hamilton and Windsor there are lots of nice little town along Lake Erie.
Hope this is of some help.