This thread definitely has my interest, being a media specialist (and having DS9 & DD11!)
I am in 2 different buildings... there are some differences, but lots of similarities.
Hot titles:
Diary of a Wimpy Kid
Fablehaven series
Inkheart series
Percy Jackson series
Warriors or Seekers series
39 Clues series
Harry Potter
Haddix books (Among the Hidden series)
The following series have cooled off as of recent (not dead, just quiet...)
Series of Unfortunate Events
Narnia
Redwall
Lord of the Rings
American Girl books
VERY little interest in:
Little House Series

Nancy Drew & Hardy Boys
Boxcar Children
Sign of the Beaver was a Newberry winner that has been removed from most libraries due to offensive nature to Native Americans.
The former librarian mentioned some of my old favs...that move only if I "sell" them.
GREAT books for precocious readers is Lois Lowry's The Giver, The Messenger & Gathering Blue. High on critial thinking skills. Tuck Everlasting is another philosophical novel that gets kids to think.
2 great authors for middle level boys are Mike Lupica & Anthony Horowitz. Lupicas are sports oriented, and Horowitz's LOOK like best sellers (kind of sound like them, too...suspense, high action) but read at a fifth grade level.