The holiday party is an opportunity to kick up your feet a bit and relax. A great time to socialize with bosses and co-workers you might not see on a daily basis.
Use this time to get to know people better and chat about "safe," fun topics, like hobbies, travel, restaurants and children; not potential land mines like work, religion, politics, etc.
If there is alcohol at the party, plan ahead to have only one or two drinks. Relaxing a little is fine, but getting inappropriately chummy with the boss or freaky on the dance floor are not good career moves.