Once you get into Ontario at Buffalo just head east thru Toronto on the QEW ( this will be self evident when you see the signs). As you approach toronto go into the downtown to see the CN tower which is worth a visit and the baseball park. ( there side by side) the downtown is huge and the roads are 4 lanes so be carefull. The get out of town on the don Valley to the 401 east. Its multi lane but taking the older kinston Rd will take all day. Go east on the 401 to the Hwy 2 crossover and follow #2 east to Kingston where you can cross by feryy to the US or on to The bridge at Alexandria bay. A great side trip should be to go on to the island at bellville. Its a medium size one day round trip which is very scenic and the beaches are great.
I don't know the US side well so your on your own to enjoy that side.
If you wait abouta month the fall colors may be excellent although you are taking more risk of rain and cold.
Come to Canada and feel the safety of knowing we don't carry,( at least very few of us).