I am 53 and my '92 R100R is much lighter than my Yamaha FJR, but they are both fun to ride. However, i can see the FJR eventually being too big to move around easily. Not yet, but i am sure it will happen.
My Dad is 83. He has been riding for years, but found his hip was bothering him so he couldn't throw a leg over a bike any longer. He bought a Yamaha Majesty 400 cc scooter and loves it! We occasionally go for rides and the scooter is very fast, easy to move around, really low center of gravity, and has great wind protection. He can even put a couple of bags of groceries under the seat. Dad rides with guys on cruisers and they are impressed with how easy he can move it around.
I LOVE riding scooters, but usually keep it to 50cc. Small scooters are the only bikes i have ever owned that I can ride with the throttle wide open all of the time. I ride my scooter mostly in the country - it is like riding a bicycle but you don't have to pedal - but I also use them in town. Scooters just plain work well, so don't think of them as the end of motorcycling. New scooters are really motorcycles in a slightly different form.