For your age kids I say electronics. At home I was always pretty stict on screen time but I threw it all out the window when we traveled. Even now the youngest is 11 and it is pretty much the same. Download a tablet with games, apps etc. be sure you have a DVD player for the car. A few good movies can help a lot. Try your best to keep them sleepy when you leave. Dress them in travel clothes when you put them to bed. Have everything ready to go and don’t wake them until the last second. Keep the car quite and don’t talk to them. While traveling, try to make the most of stops. If you stop for fast food, choose a place with a play area and let them play while you eat and them get them food to go. Also grabbing food from a fast food drive through and stopping at a rest stop is good too. Pack a ball for a bit of exercise. Reality is we rarely stop much when traveling to a location. About every 5 or 6 hours. Return trip home we take it much slower and stop more. Beyond electronics, color wonder sets, a few action figures, silly putty, a few pipe cleaners, a manga doodle, a book to read or for you to read out loud or maybe a sticker book can be fun. Snacks are great too. Some healthy, some just for fun. Family games are a huge hit for us. 20 questions, liscene plate games, etc are fun.