Why do they hide all the good books here?
In my local library (Birmingham Central), the children's section is on an entirely different floor, with miniature chairs, decorations in pastel colours, and, once, palm trees made entirely of coloured balloons.
Now, the other day, I reserved a few books - namely,
Bridge to Terabithia and Christopher Pike's
Weekend. I noticed that, although I'd be picking them up from the main floor, the children's section had several copies of Pike's books. So, when I returned
Bridge to Terabithia yesterday morning, I decided I'd return it to the children's section, then go ahead and explore their teenage shelves.

Honestly, it's amazing how nerve-wracking that was. I felt like an imposter. I'm twenty years old, and told that I look older. I felt like Gulliver walking into Lilliput.
Once I'd got over the initial embarassment, it wasn't so bad. The staff were friendly (it looks like they shift them between floors, so I'd seen a lot of them before), and none of the small children even looked at me. It also helped that an older man was in the queue in front of me.
I never made it to the teenage section, by the way. The Discworld Big Comic,
Mort, grabbed me on the way past.
It's interesting how the books are segregated, by age. As I said, I found
Mort in the children's section, and it was called a Big Comic. Neil Gaiman's
Sandman series are upstairs, in the Graphic Novel section. Now, Gaiman is scarier than Pratchett, but they're not terribly different. And, in fairness, Death is one of the main characters in
Mort.
A lot of children's books can be equally enjoyed by adults, too. While many are quite vapid, and assume that young = stupid, some are interesting. They're the kind of books you get more out of, every time you read them. Things like
Peter Pan or
The Little Prince, for instance. They're obviously children's books, but there's a lot in them for adults as well (honestly, if you've never read them, go take a look - you'll be pleasantly surprised).
The Discworld books and the
Harry Potter series have both been given special 'mature' covers, so adults don't feel silly reading them. This is essentially the same as putting a different picture on the packaging for hair dye or moisturiser, so men don't feel silly using girly products.