Billy,
You're on a very smart track here. Not only will this help you meet your immediate needs of leasing to hopefully more responsible and careful tenants, but you're setting yourself up well for a growing market - that of retiring boomers needing housing.
And we're talking about 58 year olds, or 63 year olds, or more active and independent mature people, as opposed to 96 year olds, who may not be as likely to live independently, if at all.
Where Gene and Justin are correct - you can't indicate a preference for any specific age group (unless it's set up as an age restricted community), but you can be sure to APPEAL to the preferences, likes and dislikes, and subconscious "ques" that will attract older tenants.
Here's the ticket to marketing to the mature crowd. There's a marketing expert that totally appeals to marketing to this group, and he has a book, "77 things to know for marketing to the 55+ crowd," or something like that.
Bottom line, just find books and other material (there's a ton of it out there) on how to market to that crowd and you'll attract them.
Hope that helps.