Honestly, I would paint them. First, you say that's why you bought them. Second, everyone has wooden chairs that look like wood. I'm all for making the chairs look both fun and unique. Plus, while the design is really nice, leaving them as plain wood gives me a stuffy feeling. If you plan on using them in a formal situation then wood is great. If you plan on having the room they're in be more fun and cheerful, I say paint them!