This section of the forums is a good place to voice suggestions such as this one. I know from experience that the admins who make such decisions will see your suggestion there, whereas the spoilers section is as you say, rather crouded, and your idea might get lost here.
While you are there take a look at
my suggestion of a particular spoilers child board (Sub forum). Within that topic is a good explanation (from an admin) of why the admin's are hesitant to open a new DF board. My suggestion would also result in several of these stickies getting placed elsewhere too.
Oh, and I agree, the bulk of the book club threads have already served their purpose and should be allowed to decay.