I flew my Skyhawk to Alaska in 2007. Went thru Cut Bank Montana, Cleared canadian customs at Lethbridge, Red Deer, Grand Prairie, Fort Nelson, Watson Lake, Whitehorse, Northway, Fairbanks.
Get a satellite phone before you go. Most pilots that fly up there carry them.
Call ahead to make sure they have fuel or you will be stranded. I talked to pilot that was stranded at Northway for several days waiting for fuel.
Someone said that the trip is all about weather, weather, weather, he was right. On my trip I experienced hail (twice), tornados, fog, rain,rain,rain, low clouds, limited visability, and mountain tops obscured by clouds (for days). In 2007 the only weather reported was the weather near the cities, In-between the cities it was just a guess.
BTW, getting into Canada is easy, getting back into the US is hard, Make sure your completely legal and have all you're paper work including you customs sticker.