Well, I would advise against mentally demanding routines for a retirement home (from personal experience). But before you worry about my experiences, I would say talk to the people who work there. They will be able to tell you the cognitive levels of the residents and from there you can figure out what would be good to perform.
My first regular performance area was a farmer's market where I would busk. I also performed at magic club meetings. Wasn't very long before I started doing private parties and then mixing fire, circus, and magic together for paid gigs.
I personally believe there are few things that will both humble and hone a magician faster than busking. You can get so much "flight time" as it were when you busk. Because you just set up, do your show, then let the crowd disperse after tipping you, and do it again. And again. And again. So on.
But you have recently talked about wanting to shift towards a mental performance style - so I wouldn't advise necessarily sticking with busking for too long. Busking pushes one towards a particular performance style because that's what works. Generally comedy.
But the thing is this - crowds have no investment in you. So you have to entertain them or they will just walk away. Doesn't matter if you're in the middle of a trick, they'll just walk off. Once you get good at drawing a crowd and getting a steady hat at the end of your show, that's a good time to start trying to book strolling gigs, or parlor shows.