The US would be quite hot then, well, bits of it would be. I'd do a cross-Canada trip, maybe mostly by train? Do a week in Newfoundland, a few days in Cape Breton Highlands National Park, a few days in Quebec City, a week in Montreal, a few days in Ottawa, a week in Toronto, some time in the Niagara Escarpment, a bit of time in Winnipeg (go up to Gimli etc), some time in Saskatoon, lots of time in the rockies, and some time in Vancouver and Victoria.
Hmm, only west to east would be wiser, for better jetlag ...