I feel better knowing I'm not the only person in the world "welcoming" co-workers in such a way.
We've done the sticky note thing- lots of fun
We had people collect competitor "paraphernalia" and put all of the desk and have them "guess" what's been going on since they were gone.
We took everything out of area (computer, files, supplies) and boxed up all of their personal stuff and left it on the desk with a note from "management" that said we had heard they were having such a good time and since they didn't check in at the office we thought they'd like a permanent vacation- signed "The nameless bandits".
The cost of preparing for vacation - a few late nights at the office
The cost of going somewhere for vacation - a couple thousand bucks
The cost of coworkers who care so much (they mess with your stuff while on vacation)-PRICELESS