But meshing two families' travel styles isn't always easy. Disagreements can arise over everything from schedules to choosing whether to hike or shop. "Group needs compete with personal needs, so you won't get to do everything you want on a multifamily vacation," says Matthew Purinton, a family therapist with the Council for Relationships in Philadelphia.
Before you start packing, talk openly about the areas where you may be out of sync, advises Marybeth Bond, author of 11 travel books and blogger at GutsyTraveler.com. Here's how to head off potential conflicts so you'll come home with your friendship intact -- and a Facebook page full of memories!
1. Settle money issues upfrontDon't book your hotel rooms or tour package until you have a firm commitment from the other family, along with their half of the deposit. (Make sure everybody understands that the deposit is nonrefundable.) "Nothing will fracture a friendship faster than if you book the reservation and make all the plans, only to have them back out," says Bond.
2. Plan a meal strategyYou may want the freedom and variety of eating out every night; your friends may want to save money by cooking their own dinners. Decide on a meal plan that suits both families' needs and wallets before you leave town. For example, you might splurge on one fancy dinner and take turns cooking the rest of the week.
Both families should contribute money to a "grocery pool" so you won't need to keep track of receipts and divide up bills at every meal. Got picky eaters? Pack foods and snacks your kids will eat, even if it means serving them pasta every night.
3. Schedule some alone timeTogetherness is the point of group getaways -- but being joined at the hip is not. If your friends aren't into fine art, they'll resent being dragged to museums when they'd rather hit the mall, says Purinton. Strike a balance between doing activities together and going your separate ways.
4. Discipline with careLet's face it -- kids aren't going to be perfect angels all the time. But it won't be fun for anyone if you spend the whole trip nagging and scolding. If your traveling companions have a different parenting style than yours, be prepared to follow their lead with your own kids.
But what if your friends' child is the one acting up? "Tread lightly and pack your patience," advises Bond. If he's doing something dangerous or inappropriate, speak up, but let his parents set the punishment. "It's OK to say, 'Don't jump on the chair,' but it's not okay to tell the child, 'Now you can't go on that roller coaster," says Purinton.