I know what picture books I like; but that doesn't always translate into good storytime books. Given time, I can track down some titles.
Often, an adult is looking at me with an "it seemed like a good idea at the time" expression on his or her face as they explain that they volunteered to read a book to their child's class and now they need that book for tomorrow. (And yes, it's probably 15 minutes before we close.) And suddenly, as they stand in the middle of the library full of picture books, the adult realizes: It's not that easy, is it, picking out a good storytime book?
No. No, it's not. Which is why we have our various Reader's Advisory resources. A Fuse #8 Production has a great list of Sure-Fire Storytime Hits. I'm making sure I have office copies of all and that a print out is by the reference computer.