Your quality of life will drop like a brick if you are not in good health as you reach your golden years. I would choose an area with a progressive medical industry.

West Michigan is pretty nice. Lots of medicine, blue sky, all 4 seasons and there are many philanthropists driving the recreational side of life . There is a bit of an unemployment issue, as many manufacturing jobs are being sent overseas but if you are retired it wont matter much.

Another thing I would consider are the chances of a natural or un-natural disaster.