
On a more serious note, I think until recently I had no watches in my box that I would class as 'elegant'. I could make a case that there are a couple there now. For my own personal criteria I would probably be more strict on a couple of things (although there are always exceptions to the rule):
1. Size - 39mm max for me. 40mm is getting just a little too big on my wrist to be elegant.
2. Complications - nothing more than a date otherwise it's not simple enough.
3. The presence of a seconds hand is a must - there is nothing more elegant than the sweep of a seconds hand (whether center-seconds or small-seconds). For that reason, while a quartz watch can be elegant, I find the sweep of a mechanical seconds hand to be more elegant.
4. I personally don't find Arabic numerals that elegant so it would generally be batons or roman numerals for me.
5. Steel or gold only. Bronze, titanium, ceramics etc. don't fit the 'elegant' bill for me.
6. While the topic has focused almost solely on the front of the watch, there is certainly some level of elegance I find in seeing a beautifully decorated movement on the reverse side.
Now I mentioned there's always an exception and I'll be the one to invoke Iain's rule and say that I find the Bel Canto Classic elegant. It breaks from most of the guidelines discussed in this thread so far and almost all of my own takes above. It's 41mm diameter, 13.2mm thick, titanium, doesn't have a seconds hand, has the complicated bridgework and a closed caseback. Yet I find the guilloche dial and roman numerals give it something, and particularly in a way that is completely different from the original Bel Canto.