If its a vanity site why even worry about rankings, SEO, or even reading about SEO. My philosophy has always been not to step in the way of somebody trying to make a living. Obviously many don't feel that same way. Their own vanity is more important. That's life.
outland88, not sure if I should be insulted, agree with you, or just laugh. It depends on how you define a "vanity site". If the definition is restricted to personal pages with wedding photos, baby pictures, and/or why the author doesn't like a high school teacher -- well, I'll agree. It's a vanity site, and it is unlikely searchers (other than family and friends who know specifics to look for) will have much interest.
OTOH, if you mean non-commercial sites offering unique information of interest to significant numbers of people, I strongly disagree. (I vainly kinda have to, because I'm author to several such sites. ;) ) There are a large number of very informative, and even "fun", educational sites, historical sites, hobby sites, etc., that might well be considered authorities. IMO the majority of searchers would be more interested in finding unique, informative gems than dozens of cookie-cutter [Buy Now!] sites.