I think Sun surfer's approach in his opening description of the club is really very good indeed.
But possibly, the literary angle could be further tweaked. I'll share a few of my thoughts though I don't know if they really add anything significant. Perhaps they might form a platform for further discussion--if anyone wants to do so. If not, well, here they are anyway.
Defining "literary" is difficult because "literature" itself is such a vague term. But if we are using the term qualitatively--personally, I would say that a literary evaluation--at least for the standard literary genres-- depends on excellence of writing, significance of theme, and an effective formal development.
Of these (IMO} the most important factor is the first.
I went to
A Dictionary of Literary Terms by J.A. Cuddon who makes an attempt to define "literature". Here's what he comes up with.
"If we describe something as 'literature', as opposed to anything else, the term carries with it qualitative connotations which imply that the work in question has superior qualities; that it is well above the ordinary run of written works. For example, George Eliot's novels are literature, whereas Fleming's Bond books are unquestionably not."
However, for our purposes in the club it would seem that sometimes the works chosen may not be from a traditional literary genre. Cuddon again:
"However, there are many works which cannot be classified in the main literary genres which nevertheless may be regarded as literature by virtue of the excellence of their writing, their originality, and their general aesthetic and artistic merits."
Among the many examples given in this latter area he includes such works as Augustine's
City of God, Gibbon's
Decline and Fall . . ., and Runciman's
A History of the Crusades.
So clearly we should always be looking for something special in our choice--whatever genre it comes from. I feel that there are touchstones we can use to evaluate whether or not a work fits the definition of "literature" as Cuddon expresses it. We can examine some of the features mentioned such as originality, beauty, vision, etc. If the proposed book is only another example of a particular topic--even if competently written--and doesn't add something special to our understanding--then it probably isn't suitable for the literary club--though it may still be eminently worth reading for anyone interested in the area.