I was thinking this morning about the impact on the House if seniors turn en masse against Democrats in the next set of elections. I thought about where the major senior communities are (Florida's Gulf Coast, S.C., west of Phoenix, Leisure World) and how those districts have been voting, and it seemed like they were already heavily Republican. The exceptions are the heavily northeastern retiree communities in FL-19 and FL-22.
Then I remembered where I'd seen a list like this... Social Security recipients by district. The numbers in some districts are inflated by population growth since 2000. However, it does confirm that most of these districts are represented by Republicans. The exceptions are districts where young people have left a retired industrial/coal workforce (MI-1, VA-9, WV-3, NY-27) plus NC-11, but by and large you'd be hard-pressed to define a set of districts that leans so heavily Republican.
http://www.techpolitics.org/congress/ssa109jan05.php