I think it would be nice just to keep the one thread. Maybe edit the title to "Mindless Chatter thread. Come join us!" or something like that to try to encourage the people who get put off by the high post count?
Yeah it's fine if you guys want to choose another title. I've seen titles like "The So-and-so Cafe" that are intended to give the impression of a casual thread to sit down and gab in for anyone who feels like it.
Maybe on the 1st of every month we start a new one. It gives newbies a chance to join in without a lot of backreading. It could be Mindless Chatter: June Thread or whatever we decide?
Yeah, what ^^^ said.