I am 71 and can no longer ride with traditionally shaped dropped bars. I have gone to a couple different handlebars, with one still being a drop bar, the Ritchey Beacon bar, 80mm drop, 65mm reach and 36 degree flare. The other bar I am using is the Velo-Orange Porteur bar. This is shaped a bit like a mustache bar, but narrower and less curvature, and a 15mm drop, or rise. Keeping my neck and shoulders in a more neutral position equals comfortable riding for long rides. I cannot get as aerodynamic, but that is a small sacrifice for the level of comfort it provides me. I was skeptical of the Beacon bar due to the wide flare. It took very little time to get use to it, and I was a bit surprised at how much I like it. Also, Pro has the PLT drop bar, more traditional look with 103 drop, 65mm reach and only a 10 degree flare. It works well, but I cannot stay on the drops for as long as on the Beacon bar
Another thing that has helped me, I stop more often to get off the bike for a couple of minutes just to give my neck and shoulders a break and a bit of easy stretching, and to just enjoy the view. I probably average a stop per hour, affected by how I am riding and how strong a head wind is.
Ritchey Beacon bar.
V-O Porteur Bar