As a former coworker of mine once said: "As I grow older my goal is to live closer and closer to the equator." Obviously, he didn't like cold! Although I'm the same way. I'm happy where I am so far as climate.
Medical care and transportation are my biggest issues for retirement. I want a location that has good, close medical facilities and that I don't have to drive everywhere I go. I'd prefer a well-done public transportation system with elevated rail and bus combos, but that's hard to find. I'd settle for good bike paths.
I'm hoping that as the baby-boomers retire and that as demand for elderly accommodation grows, new cities will be built FOR retirees with ground-up design for non-auto transport and lots of green space. Barring my finding such a "designed community," my only hope is to push my existing city for the designs that will be needed for the future.