You posted your comment on the Uxmal article, so I will begin there. To be honest it is not the best option. Chichen Itza would be much easier. As for other places in Yucatan, like Merida, most of the sidewalks now have access. Some of the public buildings which are very old may not, but there will be lots to see. Be sure to check with your hotel as far as their access goes, not only in public areas but also in the hotel room.
Happy travels,
Juanita Stein, Editor