On the debate over YA, I'm somewhere in the middle of what's been discussed here so far but seeing issybird disparage it I would like to stick up for it.
I really like YA. I don't read it all the time but when I get to it I enjoy it and have many YA books on my to-read list, as issybird probably knows, in addition to having nominated YA books for the club from time to time and nominating the category this year and the other. I think what it is that I like about them is that many feature main characters full of wonder at the world with the sense that anything can happen in their lives, usually because they are young with an entire unmapped life ahead. But even without that, there's almost always a sense of discovery in YA and sometimes a sense of adventure without necessarily dissolving into the "action" or even "thriller" genres. These things can happen in non-YA adult fiction as well, but it happens more consistently in YA.
I think anyone with a sense of the kid within us all can enjoy YA or even children's lit. Some people outgrow it, sure, and some people need the crutch of reading to or with a child to let themselves enjoy it but there are those of us who are adults yet still aren't embarrassed to acknowledge that we can read YA, by ourselves, with pleasure if it's a good book. I may be closer to a "young adult" than some others here (though, alas, my days of having "young" attached are probably well over) but I don't think it's really about age, it's more about having a curious and open mind just as interested in the exploration that young adult books often provide as in other book genres.
As to their discussability, I would partly agree with issybird that they generally offer somewhat less to discuss between adults, but I would never paint a broad stroke saying they all are, or even most. For instance, I think there could be a great adult discussion regarding the politics behind The Hunger Games (especially District 13 and the last book). I also think The Giver could've generated a wonderful adult discussion concerning many of its themes and its ending. The Chronicles of Narnia could generate a terrific discussion on the religious aspects of the book(s) and The Northern Lights also in the opposite direction. Then there's To Kill a Mockingbird which is basically YA, The Fault in Our Stars, The Catcher in the Rye, Lord of the Flies, the superb The Perks of Being a Wallflower, and I could go on and on. All could spur some really meaningful discussion within a group of adults.
On the other hand, many adults books
don't generate much discussion here. What does it matter how good a book
could be to discuss if we don't end up getting much discussion on it? From both clubs, these books all generated 10 or less replies in the discussion thread:
The Count of Monte Cristo,
American Gods,
Ivanhoe,
Peer Gynt and
Turn, Magic Wheel. There are more but I focused on more substantial fare.
Taking all that into consideration, I really don't see a big to-do about a YA book winning here or there if that's what's voted in. Depending on the book it could possibly generate a better or even deeper discussion than some more adult and more serious books that have won. Certainly I wouldn't want to see YA winning all the time but we're not in danger of that; looking back since I've joined close to five years ago, we rarely have books that could be called anything near YA winning - The Princess Bride is all really, and
it generated two and a half times more replies than the previously mentioned discussion threads.
All that said, I may not be voting for many YA books this month because I've read most of those nominated. I'm more hoping something I haven't read wins than worrying about YA or not. Also, I'd agree with issybird on Harry Potter - while it's a great book and while the later books in the series which are longer and more mature may have some meat to discuss, the first book is very basic and I don't see much discussion other than "I liked it" or "I'd be Gryffindor". Besides, hasn't like 99% of the world already read it?
P.S. - For what it's worth re Harry Potter,
Spoiler:
Hermione should have so ended up with Harry!

Even Rowling says so.