I have been watching "The Johnny Cash Show" on DVD, definitely on the best list. I don't remember it too much but Jimmy Dean had a show too. Seems like that was pretty good.
Cash's show was one of the best musically-oriented variety shows; Not much sketch comedy that I remember, and a really eclectic mix of musical guests from country, rock, pop, and folk circles. Jimmy Dean's show was pretty good; As a little kid, my favorite part was when he and Rowlf (from the Muppets, of course) would bust each other's chops.
How about the Richard Pyror Show and Dick Van Dyke's attempt?......
They both got raw deals from NBC, but for different reasons.
As far as Toni Tennille, I think she does pop standards concerts with a lot of orchestras these days.
Remember the name of the sketch comedy troupe on Cosell's show? "The Prime Time Players"...Yeah, that name does sound familiar...That show was an attempt to recreate the Sullivan ambience by using a host who wasn't an actual performer. An even worse attempt at that sort of show happened a few years later; "Live And In Person", hosted by a fellow named Sandy Gallin, who was Dolly Parton's manager at the time. THAT...was some bad TV.