platform_family works for me, though I personally prefer the approach of using an explicit list of platforms.

I did some research on situations similar to this in other cookbooks, and I found that the community tends to prefer targeting specific platforms over targeting via platform_family. Considering just the number of Debian derivatives (http://en.wikipedia.org/wiki/Debian#Derivatives), it's understandable that it would be difficult to test or support the entire platform_family.