At noon today, Bay Area oldies radio station KFRC-FM (99.7) will drop the format it has had for a dozen years and start focusing on an audience it says has been ignored for too long: the people some are calling Generation Jones, 38- to 49-year-olds who were too young to identify with Baby Boomers and too old to be Generation Xers. With its first song, ``One of These Nights,'' by the Eagles, the San Francisco-based station will leave behind most of the music of the 1950s and 1960s, in favor of what was big from 1975 through the '80s. ``That's...