Kung Fu Panda Holiday Special (2010)
This half-hour special, set between the two movies, deals with the same themes as the series as a whole: family, choices, self-knowledge, parents and mentors. Shifu assigns Po to host an important fancy holiday dinner for a group of Master martial artists. Po is excited and stressed with the responsibility, but also dealing with his father's disappointment that he's leaving behind their holiday traditions.
It's sweet and touching, and also absolutely hilarious. There's a fantastic frenetic montage as the pace of preparations for the holiday picks up, and some completely silly sub-plots that I loved. The animation is wonderful, the voice acting delicate and lovely.
The ending gives me the warm-and-fuzzies, which is really what you're looking for in a holiday special. This is a strong addition to the series, and I'm really happy we watched it. If you're already a fan of Kung Fu Panda, this is highly recommended. If you aren't, maybe you should watch the first movie first. But you should watch the first movie anyway, because it's awesome.