hmmm, check all fluids, make sure all filters have been taken care of recently. I always like to do an oil change before a long trip just because. Don't forget the forgotten filters, pcv, fuel filter, air filter, last tune up and o2 sensor...just to make sure your gas mileage is tip top, never hurts on a long trip.
a nice once over makes it all a smooth experience. no surprises along the way.