Recently I've come to an understanding that the thank you note, once an expression of gratitude for kindness that has been received, has sort of become a source of canned responses. Thank you notes are now the yearbook signatures of the adult world. They're trite, and often impersonal. Like yearbook signatures, they mention vague things that happened and contain only the requisite number of words to be deemed acceptable, and then they end in that generic, non committal fashion with something like "Hope to see you soon" or "Stay in touch". I imagine that in the days of hand written letters, the thank you note held more weight, but now it's just an obligation someone has to get through in order to look as if they have done all of the necessary steps. This is particularly true in thank you notes that are received after a gift has been given. If someone is diligent, the note includes reference to the specific gift you gave to them. If they are not, you get a nondescript "Thanks so much for the gift", which makes you sort of want to mention to them later how you like the gift you gave them to watch the scramble where they try to remember which thing came from you. Or, even better, mention a totally ridiculous gift and imply that you gave it to them and watch the web spin about how much they really love it, this fictitious item you have bestowed upon them.
Basically, all I'm saying is that thank you notes are usually crap.