You're probably thinking of TM Productions' "The Best Things in Life", which was used by WWL, WYTV and others. The promo for WYTV was posted on Facebook some months back: https://m.facebook.com/groups/952495251429652?view=permalink&id=1187427394603102
However, the Cleveland jingle was not done for a station, it was commisioned by the Greater Cleveland Growth Association in 1974 as part of a campaign to improve Cleveland's public image. I doubt that it was done by TM, the singers sound different, and there is an entry in the January-June 1974 Copyright Office music catalog for "Cleveland, The Best Things in Life Are Here" written by Wilbur Dorfman, a Cleveland-based composer. Maybe that was a submission for a jingle for the campaign that wasn't used in the end, maybe someone else did the final song, maybe I'm wrong and it was also TM. Also, while it has very similar lyrics to the WYTV promo, the melody is different.
I am thinking TM's campaign was a rip-off of the Cleveland jingle with a new melody, and a more distinctive musical "logo" for the tag line.