Graham, what the others have said is absolutely true -- driving yourself is the most desireable way to see the autumnal coloration. But there are a couple of caveats. I recently rented a car for a few days in Ireland because I wanted to go where the escorted tour did not go. I'm a few years your elder, but I was very nervous about driving on, for me, the "wrong side of the road." Spending most of three weeks touring on the motor coach helped to prepare me for my time behind the wheel. If you are comfortable with left-hand drive, and if you plan your route carefully, driving yourself is the way to go.
If, on the other hand, you want someone else to do the driving for you, every tour company that operates in North America has a Fall Folliage Tour package. There are even cruises that sail from places like Baltimore and New Your City that feature visits in Eastern Canada where the Autumnal coloration is as spectacular as anywhere on Earth. In fact, the most spectacular I have ever seen was in the Province of Quebec. And I live in the middle of the Appalachian Mountain forests of Pennsylvania. Western North American has a spectacular show as well, but it tends toward monochromatic yellow. The East has a multicolored display with reds, oranges, and even purples mixed in with the yellow.
If you think you might be interested in an escorted tour check out www.ymtvacations.com. YMT is a budget touring company and what you buy from them is transportation and lodging. Everything else, including most breakfasts, is on your own. Even if you plan to go independently checking the tour company itineraries could be of assistance in planning your own itinerary.
Good luck, and welcome to North America.