We did a quick run with AdWords and it turned out to be total crap. The volume of searches for stuff like "family website" was abysmal and the CPCs for stuff like "family photos" was out of the water. So, yeah. We're definitely looking to do it, but not without some conversion % estimates.
I think we'd be better off giving families an option for a "public page". Focusing on SEO over SEM would be a better long term goal. The CAC and conversion numbers didn't make sense with the small test we did for SEM. then again, that might be a bad way of looking at it since we used such a small sample.