Meeting the (Science) Relatives

Continuing my metaphor from before, I'm meeting the Science Relatives. Major European Conference starts next Saturday in the Emerald Isle. It's the biggest meeting in my field. So, obviously, the most important issue at hand is what do I wear? I've only been to one other conference and it was of the isolated Northeastern variety that are held during the summer (which Labmate and I nicknamed Summer Camp for Nerds). That was a fairly casual affair (I mean, drinking with a Nobel Laureate and talking smack with Respected and Famous Scientist during the softball game is about as casual as it gets.). I get the impression that this one might not be at that level of (in)formality. So, I'm calling on you, oh-all-knowing readers, what does one wear to a conference?