I've been working on a model for a bookstore for a couple of years. The key is attracting people to the space. Repeatedly. And once you have them there offer rewards for reading and buying books. If I'm in your bookstore drinking a delicious coffee and munching on a stuffed croissant and you offer a discount on the very book I've been meaning to read for a while, I'll buy it.
The space is filled with books, smells amazing (that sacred dusty book smell mixed with bakery and coffee smells), has comfy seating, games to play, plenty of plugs (charge for electricity rather than wifi), free fresh baked cookies(on the spot wafflecookies) with any purchase of a book (cannot be purchased separately!). There are various intellectual events, reading marathons, contests, and talks that attract interesting people. It's a space you want to be in, to bring your friends to, and you keep spending money there.
It's more than just a bookstore or a cafe or a co-working space though. It's a place that promotes books and reading, connecting people intellectually. A "membership" offers various rewards but also frictionlessly offers reading suggestions and also communal reading/commenting. Not necessarily a reading club... If you are proud of the books you've read and/or have an interesting opinion/interpretation or have questions, a common discussion space/online/app interaction space helps make this easy and comfortable for any level of socializing.
I and two of my close friends (we're all CS people) have been looking for opportunities to try our ideas out, and to learn about others' experiences. Looks like you've had a great response here but if you're still looking for ideas / a group of people with a lot of energy and ideas, let me know, I'm always in the area at some cafe or another! :-)