Do jeans qualify as semi-formal attire for a Christmas party?

My wife and I usually attend one or two semi-formal events at Christmas.  I'm inclined to wear jeans because that's what's most comfortable, but are they dressy enough?

I usually wind up wearing pants because my wife says it's better to go too dressy than the underdress. And every piece of etiquette I can google agrees with her.  But every year, I see more and more guys wearing jeans at these events.

What do you think? And for the sake of this argument, I'm not referring to baggy, faded jeans with holes. I'm talking about dressy jeans that are more fitted with a darker wash.