Another story I'd write, were I enough of a writer to write entire stories, instead of just fragments on LJ.

Near future SF - Science has discovered the fountain of youth. The process effectively reverts a body to the prime of health, and a youthful appearance. The catch is that The Powers That Be hold back the process, allowing only those who have reached 80 years of age to be rejuvenated. The idea is that a person needs to experience getting old, frail and weak before zie can truly appreciate being forever young. The story would first explore the nature of such a society, then contrast with another society where such a rule was not in place, and no one progresses past the emotional level of late teens/early 20s.