I've obsessed a little about my computer desk, and it's fair to say my needs, and expected needs, have changed over time.
A few years ago I had a colossal office-style desk which even then was somewhat too big. It was passed on to me by a friend that was moving home and I was pretty grateful to have it (and it has now passed on to another friend). Later, when I had made the decision to move to a Mac but hadn't yet made the switch I put together the specification for a minimal desk that would hide the few cables of an iMac. I had this desk built by a carpenter friend and still use it to this day. It is an excellent desk.
This desk is still kinda huge, especially as the retina MacBook Pro came along and usurped the iMac in my upgrade plans, but to be honest it would have been oversized anyway. It's fair to say that I don't want a very desk-like desk at all; what I really want is a table, something along the lines of a small dining table. Even if i were to add a Thunderbolt Display to my setup, I don't really need a lot of space on the desk. A MacBook and a coffee cup don't have excessive surface requirements. I also don't much like or need under-slung desk drawers or other storage that I will never fill and bruise my knees against.
Which brings me to another problem with my 'office' setup: storage.
I have very specific storage needs, and they revolve primarily around various financial paperwork. Part of me want's to digitise as much of this paperwork as possible - but some of it, while it can be digitised for my own purposes, needs to be retained in it's physical form for legal reasons (tax details, payslips). There are also a few assorted items that I rarely use but need to keep available (cheque book, passport, etc.). In the short term, until I can muster and prioritise the finances for a wireless, duplex, document scanner, this is going to remain a wholly paper-based system for the most part. I think this is a job for a standard two-drawer filing cabinet.