My in-laws are a giant pain in the ass. They are very critical of a lot of our lifestyle. Hell, part of the reason I think we're broke now is because we've spent thousands of dollars in home decor and improvement stuff to make them less likely to bitch at us. They aren't bad people, but they are very stuff-conscious. They see something "wrong" in our house, or our housekeeping, and feel obligated to tell us about it.
Last night, it came to something of a head. My wife and I were both stressed, she wanted to calm me down but also wanted me to do more work. I snapped, finally... and at the end of it, we both decided that we're done playing this game. We're done spending money to satisfy them, when it won't work anyway. We're done killing ourselves every time they come into town. We're REALLY done getting so stressed out that we snap at each other every time they decide to use our home as a hotel room.
They'll be here tomorrow. They can appreciate the hospitality, and mind their business about the fact that there are places on the wall that need repainting, and that the cat has scratched up the carpets pretty bad. If they don't like it, they can each have a huge slice of STFU pie, hit the bricks, and stay at the local motel.