I've ever been to nursing homes when I was junior high school student (we had to taste the job at that time), they were exercising doing an easy stretch. I thought that was good, but kind of boring.
I've never danced Tango, and so I don't know if it is fun, but I guess it's more fun than a mere stretch.
I have to think about seniors who can't even stand alone. They can't do a step, they can only clap their hands or something. I think we should find a dance which can be danced by a person who can't stand.