Since I guess we're weighing in, I might as well too. Elegance to me is the "wow, that's clever" factor. I'm pretty familiar with trickery and theory op-style decisions, so those don't wow me anymore (magic9mushroom's builds are always the exception ). However, getting the most out of a given feat/prestige class/base class without resorting to questionably intentioned tricks? That's rare, and that's what I'm looking to see.
EDIT: Concerning optimization, I'm not adverse to seeing it. Hell, if you're given something crappy like Justice of Weal and Woe and are asked to make it good, I'd EXPECT to see some optimization, but again, avoid the dirty tricks. It's more impressive to see you do something great without resorting to questionable tactics.