River Cruise Activity Level?

Look at Grand Circle cruises. You can click for a blow-by-blow of each cruise's daily activities, plus an overall rating of activity level (miles per day, stairs, etc.), & travelers' reviews. There's also the Cruise Critic website.

I've done 11 Road Scholar programs although none have been cruises. Over the last few years I've found the Activity Level listed on the program overview page is pretty accurate. They changed the rating system a few years ago and this one is much better

Do be aware that on some cruises Road Scholars are traveling on a cruise line not owned by Road Scholar. They have apparently leased a cruise ship for the Aegean area for the coming 3 years. I noticed that they have leased entire barges for a few river trips (I was looking at the Christmas Market trip to Strasbourg) but this would not be the case with all of them. I just wanted to put this out there so you were aware they often don't "run" the cruises - the cruise line does. Road Scholar would be responsible for the activity level, however.

Have you gotten down to deciding which cruises might be of interest to you?

I would say the shore activity level can be what ever you want it to be, that is skip the canned tours if you want and plan something on your own. The replacement value of those canned group tours if you bought them would be maybe $50 a person/tour, so it's not a huge loss.

For instance if you took a cruise that included Budapest, skip their tour and get on a Hop on Hop off bus. That would run you about $30 a ticket for a 48 hour ticket. Or read this: https://community.ricksteves.com/travel-forum/hungary/budapest-itinerary-for-the-mobility-challenged

We've done 4 River cruises with Tauck and find that more and more they offer options (and they never charge for any excursions or options). Example: in Passau last summer we were docked right in the old town area and you could take an 1-2 hour guided walking tour, stroll around on your own, stay on board or climb a hill for the view. They try to accommodate differing walking/fitness levels as much as possible. You do need to be able to climb at least some stairs just moving around the ship, getting on/off, etc.

You have more flexibility to do as you wish on rivers where the ships tend to dock in the heart of the action vs being bused. The Danube and Rhone were the best for that.

Also read the itineraries in detail. If it says something like "this morning we'll go on a guided walking tour with time on your own then return to the ship for lunch" then that's a fairly light morning.

Ps - I was the driving force for our first cruise but husband has enjoyed it so much we did the other 3.

Consider AMAWaterways, a much much better experience than Viking.
Do what is best for you. Skip long bus tours and enjoy the river towns. Set your own pace.

"I would say the shore activity level can be what ever you want it to be, that is skip the canned tours if you want and plan something on your own."

This might work with Viking which is an actual cruise line but for Road Scholar and possibly Gate 1 you are paying for programming with them. You can, of course opt out of any activity with Road Scholar (although harder to do on a transit day) but it's smart to know where they peg the activity level so a person will know if this will work for them. No point in signing up for a program that is ranked Strenuous when you'll not be able to participate in the activities for which you've paid.

I dont take any of these sites too seriously, but if you check 3 or 4 and they are similar then I bet there is some truth behind it.

On the one route I picked without any regard to the boat, Viking 86% Excellent or Very Good; AMA Waterways 92%. But I would imagine the boat and the route might create some difference in result.

https://www.cruisecritic.co.uk/budapest-viking-river-europe-river-cruises_dp473-cl59-de128/mra/
https://www.cruisecritic.co.uk/budapest-ama-waterways-europe-river-cruises_dp473-cl116-de128/mra/

I'm going on the Viking Rhine Getaway cruise this summer and I found that they have many half day included walking tours of the towns that we're stopping in. They say that they have different paced tours that you can request when booking.