Best Activities for People w/ mobility issues?

I think those of us without mobility issues often overlook situations that could be a problem for others. That said: Much of Zagreb is flat, and a lot of the historic area should be easily manageable, assuming that there are curb cuts. I don't remember super-narrow streets of the type present in some other cities, the traffic wasn't insane, and the sidewalks were lively but not crazily overcrowded. However, the historic area is distinctly on two levels, and I think you may need something other than a scooter to get to the upper level. There's a funicular, but it's not very conveniently located, and I think there are steps at the top as you exit it. (I could be wrong about that.) I suspect a taxi might be the best approach, but your hotel or the tourist office can probably give you good advice.

There are some good, small museums on the upper level, and it's a nice area just for wandering around. It's very pretty and is quieter than the lower section. I'm nearly certain that the Museum of Broken Relationships is accessible, and it is fun. The naïve-art museum I fear is not accessible. It's upstairs in a small building, and I don't remember an elevator. It is a fabulous museum, though, so if you have an interest in that subject, it's worth checking locally to see whether there is an elevator that I just did not notice.

The larger museums are down on the lower level, sort of between the train station and the historic district. They have elevators, but you should probably request permission to use one. The staffers were not happy that I used one without asking. (I looked totally mobile, but I had two sprained ankles that I was trying to protect.)

I wouldn't recommend that you attempt the outdoor produce market. I remember it as being very crowded.

I haven't been to Dubrovnik or Split recently.

acraven, thank you for your helpful reply. I'll take your suggestions into consideration and sure it will all be great!!