For what it's worth I'm over 70 and I too live in a hilly area. Less than a week ago replaced my 10 year old Kalkhoff Agattu with a Batavus Harlem Ego, which was just about the only bike I could find that ticked all my boxes (those being comfortable upright riding position for a 6-footer, crank motor, full chainguard, 8-speed rear hub, disc brakes, established manufacturer and preferably front carrier as well as back). With 35 miles now on the clock, I could not be more pleased with it.
ETA Should have pointed out that I use my bikes as my sole form of transport, and have done for the last 8 years. I ride all year round in all weathers except when there's ice about. So basically it's a working bike, with occasional leisure use on 20 or so mile round trips hereabouts.