Voicemails don’t necessarily have to be monotonous or extremely jazzy or funky. What you should be looking for is a balance between the two. Whenever you call someone and their voicemail greeting is playing, it tells you a lot about who they are, as a person. Which is why, you’ve got to put a little bit of “you” when it comes to voicemail. And the best part about all of this is, since you couldn’t come to the phone, at least the callers are having a good time listening to the message.
Hi, you’ve reached (your name) office. Either I’m away from the desk or on another line. Please leave me a brief message with your name and contact number so I can call you back. If this is an emergency, call me on (your cell phone number).

When you’re closed for the holiday, it’s good to forgo your usual out-of-office greeting for a custom holiday message. Keep it cheery and brief, and be sure to let callers know when you’ll resume normal business operations.
You don’t have to spell out every single thing that you think they might want to know. Have some faith that your callers will be able to figure things out on their own. Be natural but informative.