In-Laws Want to Come for Christmas ... Again!

So my husband and I have been married for six years. I am having a hard time with what to do about Christmas. Since before we were married, my husband's parents have made the trip up from Phoenix to stay with us for an entire week during Christmastime. Three of those years we made the trip down to see them during Christmas.

I like his family but I feel like they are not allowing us to have our own family time during the holidays, so that we can create our own family traditions. I don't think his parents have bad intentions, but at this point I feel like I need to put my foot down about how I feel or they will continue to visit no matter what. I am fine with every other year, even if we have to make the trip to see them, but I have lost out on a lot of family memories with just my family because they are here for every holiday.