Most Helpful Guy
Since it is audio only...
You could always perhaps try downloading standup comedy. I don't know your sense of humor but I think I saw some Bill Burr stuff on youtube before. There are tons of comedy routines on youtube.
Since you like celebrity interviews too, you could consider downloading late night comedy shows (Jay Leno, Obrian, Craig Ferguson, etc.). That is comedy and celebrity interviews.
Another possibility is music. For long drives, I like getting bands I want to listen to but haven't had a chance to. It keeps it more interesting than stuff I know because it is unknown to me.
You could download documentaries, but documentaries tend to be a lot of visual stimuli. Hmm... I would check out podcasts. They may have documentary podcasts! I don't know off the top of my head.