ION, formerly PAX and i, has had a unique yet underdog history going from airing family and religious shows to police procedural crime dramas and sitcoms. However they have the least affiliates of all the commercial networks that existed before the DTV revolution in recent history. ion 56 WSPX in my area have the largest digital tier with six subchannels yet have a small studio in East Syracuse near Walmart. ion 51 WPXJ in Genesee County serves much of Western New York. For areas that don't even have a low-power station over the air with ION cable or satellite should have it on their lineup. Due to the vast size of the nation it'd take an eternity to come up with over a hundred markets that could use ION which could be why they could have lower ratings than my Network TV or the CW. Upstate NY I know so I could just go from there and a few select other states just to get an idea. Here's where ION could charge up:
Tallahassee (Floridas capital)
Philadelphia (even there)
Just several examples without going out on a limb.