I frequent several different teaching forums and it amazes me that this concept is so controversial. I guess there are many out there who think having a theme is just "fluff". I've always had themes to decorate my classroom with, if nothing else, it gives me direction. Changing things up each year gives different kiddos different experiences and honestly, I get tired of looking at the same thing all year. You can also make it educational-I've done China as a class theme, this August it's going to be New York City (is it sad I've had the borders in the trunk of my car already for about 4 months? :) What can I say, I get excited for a new batch of kiddos!
We've had Hollywood, the Ocean, Pirates as well-I do have some pics.
This was China-we had a "Great Wall of Writing" as well: