Know your travel style and communicate it to others - This one is pretty easy. Four of the five of us are really lazy travelers, and the less we put on our plate that we have to do the better. My wife has just enough drive to keep us from actually going comatose in the hotel room and making sure that we actually see some of wherever we are.
Be clear about the purpose of the trip – I try. I really do, but there's only so many times I can tell the kids where we are going and what we are going to do when we get there before I start making things up. I learned the hard way not to start telling stories before we cross the border though. The border guards don't like it when every member of the family has a different idea of where they are going.
Take into consideration the duration of the trip - Never mind the duration of the trip, I wish my kids would just pay attention to the duration of the car ride. I swear we've made the drive from Kelowna to Vancouver at least 100 times, yet every time the "How much further?" questions start long before the half way mark. It's almost as if after 13 years of driving back and forth they think I'm going to find a shortcut that I hadn't noticed before.
Listen, negotiate and compromise - Fantastic advice, in every other situation. My kids idea of compromise is "Let's do it my way today, and your way some time after I've moved out of the house." We may be in democratic countries, but the traveling circus that I preside over, is a dictatorship.
Decide what you are going to do every day – This is probably the best piece of advice for our family. We need to have a plan of something to do every day or we will just waste the day away. My kids once stayed in their pajamas for two straight days in a hotel across the street from Disneyland because we never officially "made a plan" to go to Disney.
Decide if some activities should be done together or alone – I wish. It's gotten better as the kids get older, and breakfast is now optional if you would prefer to get some extra sleep. After that though, it's group activity time.
Decide on a budget or how to divide travel costs – Hahahahahahahahahahahahahahaha!!!
Divide the obligations – If you're a kid in this family, you have one job and that's to pull a suitcase. If you're the wife, the rest of the jobs are yours.
Don’t complain if you don’t have anything to say - Another brilliant tip! Don't tell me you don't care what we do and then complain all day. Actually, even if you do care what we do, don't complain all day. Let's just shorten this rule to "Don't complain".
I'm really glad that there's no scoring system on this, as I'm pretty sure we'd be barred from ever traveling together again. I think what gets us through is that we're a band of complete Type B personalities. We very rarely accomplish everything we set out to do, but we almost always have a fun time doing it.
Most importantly though, is the fact that the objective when traveling as a family is different. It becomes a lot more about the experiences and memories of doing things with your siblings/parents/kids, and less about the destination or event. Those days when things go bad, and there will always be those days, just get blocked out and replaced with the good memories (Except for the J. Paul Getty museum. When the day goes that far south on you, it gets it's own category of memories.) Ultimately it's a decision of who you want to share these memories with, and by that criteria we are perfect for traveling together.