I have a friend who goes to the beach every year and stays in a rental house. Her parents go and her in-laws do too! They all vacation together, and she said they get along well. I could never imagine my parents and my in-laws vacationing together. They rarely see each other, which is probably good, since they are very different people and might get on each other's nerves. I'm curious to hear what the relationship is like for other people's parents and in-laws.