I haven't considered overnight talk radio to be worth staying up to listen to ever since Larry King left his radio show. Larry knew how to hold an audience.
There are three basic reasons for Larry King's success, when compared to Coast To Coast today.
First off, Larry's talk show hours were earlier in the evening, (at least in the Mountain and Pacific Time Zones). His show started at midnight Eastern Time, which was 9 p.m. Pacific. C2C starts an hour later.
Secondly, Larry also interviewed big name authors, big name entertainment figures, and many sports figures. Oftentimes it sounded like a sports talk show. At the time, there were no national sports talk networks. I don't even think there was a national sports talk show, although there were a few local sports talk stations, some of which might have had some nighttime reach.
And third, Larry's show was the only national, live, overnight talk and interview show. There was no competition in his particular field of talk radio. Other overnight or late night talk shows were just a host talking to the callers about various issues and taking calls while giving advice, like Bruce Williams or Sally Jesse Raphael.
Larry "held" an audience because his show was similar to an interactive version of Johnny Carson or David Letterman, minus the musicians on stage. The guests were bigger names. Callers could conceivably ask these big stars and big name authors and sports figures questions. It had an appeal for those reasons. And Larry was an excellent interviewer.
I'm not denying any overt appeal due to Larry's ability. He was a great interviewer and his anecdotes livened up the show when needed. I used to listen to Larry King every night. I bought some books by authors he interviewed. But one of the reasons his show was so successful was it was the only game in town.
Right now, one could say Coast To Coast is the only game in town in overnight talk, along with Red Eye. But radio is not the only game in town -- not to the extent it was in 1979 or 1983 when Larry King was indeed talk radio. The internet offers thousands of alternatives, from streaming movies to social media to podcasts. Even if Coast had the hallmarks of Larry King during his heyday, it wouldn't be much more popular. The content field is so much wider in breadth today.