Frontier DEN-CVG, FAT, EUG
http://www.bizjournals.com/denver/ne...ml?ana=RSS_wid
This feels more like "classic" F9 routing than recent forays into small airports on the east coast. Interesting to note that DAY didn't work out because of WN.
CVG-DEN-CVG can even be done as a day trip for business travelers.