I reported on a blog I maintain as part of my official duties about a new guidebook published by the International Longevity Center and Aging Services of California. Media Takes: On Aging offers prescriptions of what words and terms to use–and not to use–when referring in writing to our older population.
As far as sensitivities go, the age of 55 seems to be the turning point. Those below 55, for instance, find "senior citizen" perfectly acceptable. Likewise with "retiree." Don’t call anyone 55 or older a "retiree."
Also, make sure not to use "old" as an adjective, as in "old coot" and "old fart." Those really go beyond the PC pale.
As for me, who qualifies easily above 55, call me anything you like. If it’s in the Comments section, I just won’t print it if I don’t like it. LOL