library themes

I like to have a theme in my elementary libraries.  I like to have just one for the year because I do not have the time or resources to switch the main theme more than that.  I have specialty themes that I do in the interim but one main theme.  Marion Elementary is goingo to be Under the Sea (since that is the Tigerton summer school theme and I already have a lot of props done up for it).  I am currently looking for another theme for Tigerton.  I've done frogs, Dr. Seuss, reading wizards, clue, camping, teddy bears and a few others.  I am looking for some ideas on the under the sea theme as well as another theme for Tigerton.