and instead do something linked to your school's curriculum. We found most students seem to know only the Disney versions of the fairy tales, but not the real versions, which leads to difficulties with inference, idioms, and so on. They get enough of the commercial world everyday anyway.
We skipped a theme and did monthly and weekly displays that connected to curriculum, holidays, traditions, current events, and so on. It kept the kids interested and the displays never got old. Some required student input; we had a fairy tale display and had the kids add anything that came in 3's - three little pigs, three little kittens, three bears, events in fairy tales that came in threes, then it expanded to the branches of government, three innings in baseball... it was amazing what the students came up with!
Anyway - the library is the best classroom in the school