I suggest Kalamazoo, Michigan, the home of Western Michigan University. Having lived in both Kalamazoo and Ann Arbor, I would say that Kalamazoo is similar to Ann Arbor in many ways (i.e., cultural offerings, progressive politics, a good health care system, etc.), but the cost of housing is much lower. Kalamazoo does get more snow than Ann Arbor, but the summers are great (maybe 2 weeks of temperatures above 90). There are also many good places to run in Kalamazoo—such as the Kal-Haven Trail State Park, a former railroad bed that goes 33 miles from Kalamazoo to Lake Michigan.
As a retiree, you probably don't have school-age children, but another advantage of living in Kalamazoo is that every K-12 graduate of the Kalamazoo Public Schools gets a free college education at an in-state school (e.g., University of Michigan, Michigan State, Wayne State, Western Michigan, Eastern Michigan, Central Michigan, Northern Michigan, Grand Valley State, Oakland University, Ferris State, etc.). This generous gift has been funded, in perpetuity, by a group of anonymous donors.
Overall, except for the winter months, I think Kalamazoo would be a great place to retire.