1. If they have a good time, that's great. But don't spend too much effort trying to make them have a good time. Don't be too disappointed if the vacation does not work out for them. You can't force someone to enjoy themselves. Also, teens often get a lot more out of a vacation than you think. You just don't get to see it: "Like I'm going to say, 'Oh. Wow. This is great.' to my parents. I don't think so."
2. Electronic devices are good. During the year, you may cut back and limit their use, but on family vacations - especially for long car trips - they're a blessing. You'll definitely get less of this: "I'm bored. There's nothing to do." There's always something to do when you have the electronic world at your finger tips.
3. Try this philosophy: Every day is a new day. No matter how sullen and bratty your teens were yesterday, start each day fresh. No carryover punishments. No staying mad at them for something they did or said yesterday. After all, if they go through the whole day under a cloud, who's the one who mainly gets punished?
4. A corollary of the above is that, in regard to your teen, vacations are a time to bring out Mr. and Mrs. Cheerful.
"Isn't this just great?"
"No, this is boring and stupid and I will never go on a family vacation again, no matter what you do to me."
"Just smell that fresh air. You don't get air like that at home."
"Yes, I do. Whenever I turn on my air conditioner. Can I get money for bus fare back to our house?"
"Yep, this is the life."
5. The more you can trust your teens to be on their own, the better. They will have a better time. It will be more of an adventure for them. There will be less time for you to get on each other's nerves. You have to use your judgment about what's safe. But within acceptable degrees of risk, the more autonomy you can give them during a vacation, the better.
"Mom, Dad. It was so cool. There were these guys way at the other end of the campground who showed me all these cool illegal drugs. And they told me these real sweet ways I can steal money from you guys so you won't notice it so I can buy some drugs from them."
6. Swim. A lot. There is something magical about swimming pools and beaches. Kids of all ages just like them.
7. Have plans for each day, but do not be bound by whatever those plans may be. If something is going poorly, drop it. If it's going well, keep going.
8. As always, but especially on a vacation, don't respond to every bit of backtalk. That only pours fuel on the fire.
9. Vacations are good times to make exceptions to rules. You always have the excuse, "This is just for vacation." It avoids fights.
10. They want to go to a mall? Let them go to a mall. If you're lucky, maybe you'll even witness this:
"So, how was your family vacation?"
"Don't ask. No, actually, it was okay."