Well, if you knew them, you wouldn't be saying that. I don't see what is polite about them advising us of THEIR plans. He told DH that he and his family wanted to visit, he didn't ask if we were up for it or anything. It was more like, "we want to come and this is the day and the length of time we will be there; is that ok with you". There is a bit of history here that I won't go into, but suffice it to say that I have had enough of him and his family.
My "polite meter" with them stopped working a long time ago. Does that make me a snob? Maybe, but I don't really care. DH understands though and isn't resentful about it.