When I was 62, I got myself a Canyon Endurace, with a CF frame, disc brakes, and 11 speed 105. With it, I ramped up my annual mileage from the 1000-1500 range up to over 6000. It's an Endurance bike, but it's always the fastest bike I own, so you don't necessarily have to give up speed for comfort. With your budget I'd look at something like the Endurace CF SLX 8 Di2, which will give you 12 speeds with electronic shifting. But, you know, I'm a Canyon fan boy.
