Originally Posted by leftover_salmon
How about whom do I tell? Do I tell the Managing Director (i.e. very senior position) with whom I work the closest, or the head of the group, who is technically my boss but much less involved in my day-to-day work (though he's still only ~20 feet away)?
Here's how I've handled a similar situation.
1. Draft up a letter, addressed to the group head, thanking him and the company for the opportunities you've had during your time there.
2. Look for an opportunity to catch your MD off the floor (at the coffee shop would be a prime location).
3. Mention that you've wanted to speak with him about something - say that although you are probably breaking protocol by talking to the MD before your direct supervisor, you value the relationship and wanted to let him know first. Explain that for reasons entirely unrelated to your work, you've decided that living in [town] isn't right for you, and you've accepted a position elsewhere which fits your living arrangements.
4. Before the rumour mill has a chance to start turning, front up to the group head and pull him aside. Repeat step 3. Hand him the letter at the end of the conversation, just saying that you put it in a letter to make things official.
Again, if you're front office, or working on anything that involves much IP, they'll likely march you straight away. Discreetly pack some things beforehand, and don't let the door hit you in the ass on the way out.