Traveling w/ newborn, WWYD?

My husband and I live about an 8 hour car ride away from his family. He really wants to go visit them for Christmas when our baby will be 4-6 weeks old. We were thinking maybe doing 4 hours then staying at a hotel for a night then finishing the last 4 hours but I'm still kind of iffy about it. Has anybody had experience traveling with a newborn? How was it? Any advice?