Since i travel cheaply I have met several of the elderhostel tours in my travels accidentally. At least in Europe, they seem to choose centrally located small hotels and allow some free time for personal exploring. However there seemed to be "lectures" at meals which seemed like they were"official" lectures and not just some windbag
I support them getting tours together for older people. Until I am older and/or more inform or mobility-limited, I will ,iely not use their tours Right now I would have a hard time with being limited by the most limited of the older people I have met on these tours who had a lot of trouble walking , hearing etc. The tour groups seem to be big - 20 or more - at least in France and Spain.
I do get their booklets on tours and I found the prices for First World travel locales rather expensive. Perhaps for more exotic locales it's a better deal re; access and level of comfort.