We travel often to visit family and over the years I have found there is a list of tasks and procedures I always complete as I prepare for each trip.

One week before departure, I start washing dirty clothes I might want to pack. Then I move on to any other dirty clothes, followed by towels, bed linens and the final load of laundry the day before leaving consists of any clothes we dirtied during the last few days.  
Goal= Leave no dirty laundry 

I pack each child about 5 days before departure.  I lay everything out organized by day making sure everything is there that they might need (underwear, socks, accessories).  Then I check to see what shoes I need to take based on all the outfits chosen.  I try to pack only 2 pairs of shoes per child (tennis shoes and dressy shoes) so, I try to keep that in mind as I choose outfits.  Finally, I pack their toiletries and bedtime items.
Goal= Kid's suitcases packed and set aside 4-5 days prior to departure

My husband finds it amusing how much cleaning I do in order to LEAVE on a trip.  In truth, it is probably more detailed than when guests are coming over to our house. I cannot stand leaving a dirty house and find it very refreshing to come home to a clean house with fresh linens after traveling for a week or more.  The downside is this preference makes for some mad cleaning for 3 days before a trip.  Floors are swept, mopped, vacuumed in all rooms.  Baseboards are cleaned.  Every surface is dusted.  Kitchen gets a deep cleaning (refrigerator, stove, cabinets, etc.) and all bathrooms are scrubbed.  All the toys and miscellaneous items are organized and put away.  Finally, right before we leave every dirty dish is cleaned and fresh linens are put on every bed.  The added bonus to all this cleaning is that it allows me to relax the day after returning home because there aren't any tasks to be done!  Most of the time, I don't even have laundry to complete upon returning because I wash all our clothes at Nana's house before heading home.
Goal= Leave a clean house; return to a clean house

Travel Bags
Regardless of which side of the family we are going to visit, the drive is long and having plenty of in-car entertainment is vital.  Two to three days before embarking, I put together a bag for each child and and an electronics bag.  The kids' bags have coloring supplies, books, small toys and a few new items as a surprise. We take two Tag Jr reading bags as well.  The electronics bag holds the iPad, nook, chargers, laptop, cameras, etc.  These bags combined with our van's movie screens and dvds help make for a very pleasant trip. :)
Goal= Happy Passengers

More Packing
I wait to pack the suitcase for my husband and I 1-2 days before leaving.  I pack in a similar fashion as when I pack the kids.  Our suitcase isn't completely finished until the morning of departure when the toiletry bag is added.  I also grab our pillows that morning.
Goal= Parent suitcase and ready by morning of departure

Snack Bags/Cooler
The day before leaving, I pack a snack bag for the ride.  I choose things that are not super junky and not messy.  I also make sure and have some special driver snacks like sunflower seeds or peanuts.  My kids rarely eat in their carseats so it is a special treat to have snacks in the car on long trips.  I pack a cooler with drinks and add ice on our way out.
Goal= Occupy kids and buy time between stops; keep the driver awake

Load the Car
Hooray!  The time has come.  All the preparations are finished and we load the car the night before leaving.  If we have multiple stops, we keep that in mind making sure things we need first our last to be packed.  All travel bags and snacks are accessible to the passenger and all that's left is to leave.
Goal= Be prepared to hop in the car and leave bright and early

For me, all of these tasks pay off in the end.  The drive goes well, we enjoy our vacation and I love coming home to my spotless house!