I've traveled across the country and back with a 2 year old and a 6 year old so I know how to make a long trip more pleasant. lol
Spit the drive time up about every 3 hours and don't be afraid to stop often to grab a snack/drink, use the bathroom or just look at some roadside attraction for a few minutes. If you have someone who really likes to drive or someone who hates to drive then adjust accordingly. I drive for a living so I can usually do long stretches of night driving and not worry too much, but everyone is different and making sure you get there and back safely is a big deal.
Bring quality snacks, to keep you alert. Candy bars, coffee and soda are good for a short buzz but cashews, almonds and other healthier snacks really do help on a long trip.
Get your entertainment squared away as well, I like podcasts but that's not everyone's favorite. I can listen to randy, meateater or Joe Rogan for hours straight and they keep me mentally stimulated. Sometimes you need a good shot of music to keep the energy up.
I'll throw in some driving tips but take it with a grain of salt: Keep your eyes moving as you drive, this means turn your head and look, don't trust your mirrors(plus, moving your head to look and clear dangers helps you stay awake and aware), Leave plenty of space in front of you(6+ seconds on the highway), don't hang out next to truckers(get around them so they can see you) and clear intersections like your life depends on it(drunks and sober drivers alike are most likely to have bad accidents at intersections, so clear them well and make sure some idiot is actually going to stop for his red light or stop sign).
