Well, being a guy, I was never exactly trained to write thank you notes. I was more told to say thank you in person, as it's much more formal that way. That's what my dad said, anyway.
However, my mother corrected me on that. I know that it's proper to write someone, regardless if you thank them in person. That's more the polite thing to do.
I don't see why someone could say that it's "women's work." I thought that wasn't really said anymore. o_o; It's just the polite thing to do...
So when it comes time for me and Rose to write thank you cards, rest assured, she won't be the only one doing it. 
You rock!
To those neanderthals that think this just isn't a "guy" thing, here's your answer. :-)