Read any book you want to and meet up to talk about them, simple! Read as much or as little as you want it's really a conversation group so if you've not finished that 500 page biography it's all good.
Honorable mentions from the previous meetup:
---Books---
The Rise of Theodore Roosevelt, Morris
North Woods, Mason
History of the World in Six Glasses, Standage
Annihilation, Vandermeer
In shadow of Englightment, Carroll
The Road (Graphic Novel), McCarthy and Larcenet
Faith in a Seed, Thoreau
Confessions, St Augustine
Kafka: The Complete Stories, Kafka
The Map of Time, Palma
Jurassic Park, Crichton
How to be a Good Creature, Montgomery
The Greek Revolution, Mazower
---Film, Musicals, Websites, TV and Stuff to Do---
Wild Wild Country (2018), Documentary about cults