OAT/GCT activity descriptions have been discussed before and most seem to think that they are all right the way they are. However, I think that steps make a huge difference in an activity level. Even younger, healthy people have knee problems that would make it painful to walk down 640 steps.
Road Scholar Greek Island trip description below.
Walking up and downhill, up to two miles per day. Standing up to four hours per day, with breaks; uneven terrain and steep stairs without railings at historic sites.
"Steep stairs without railings" would make me think seriously about that trip.
Another question: I always wonder what posters mean when they write "walking stick." Is it a cane, a wood walking stick or a collapsible metal trekking pole? When I see "walking stick" I think of walkers with their wood poles in Switzerland.