I first read The Phantom Tollbooth when I was young and think it's just fantastic. It's a story that will certainly inspire creativity! With characters such as Tock the watchdog, the Whether Man, and princesses Rhyme and Reason, and places like Dictionopolis and the Market Place (where there are, "juicy, tempting words for sale") how could it not?
I encourage you to pick it up. You can find it here if you like.