I would have thought this had trickled to you already... apparently, someone with too much time on his hands has scanned and digitized decades of TV Guide ads that appeared in his local Toledo, Ohio edition:
If, like me, you cut your teeth and built your golden legacy on Fox, NBC and CBS TV Guide ads (I thought one day my tombstone might be a TV Guide ad), then you will appreciate the joy and horror of this website.
Sincerely, Hugh G. Rection
Not included in Mr. Rection's Toledo treasure trove is the vintage Letterman TV Guide ad below. Judging by the station place-holder, we assume it never had its moment of dot gain glory.
Click on images to enlarge.