My parents are in far better shape financially than my husband and I are. They live on the west coast. They never come out just to visit us, but sometimes they "stop over" on their way to another destination, like Europe. They've done that twice in the past year---in June on their way to London, and in September on their way to Italy. In January they are going to Australia so the won't have an East Coast layover. They take long (3+ weeks) international trips 3-4 times per year, whereas we are currently trying to figure out if we can afford a day trip to Hershey park.
So no, we do not pay for their plane tickets.