Since we're all putting in our 2 cents worth....
I think Biography/Memoirs would be the only NonFiction category I would support, personally. I just don't want it to be right after Classics month. In fact, I would suggest it for August.
I would love to have a fun category in the summer (June and/or July) and a fun category in December which for me would be Fantasy (in July or December) and/or Science Fiction (in June or July).