Remember back in the old days? We had MAD LIBS! The entire family can enjoy adding words to make silly stories and maybe learn a thing or two about nouns, pronouns, adjectives, etc. The Dollar Tree carries them.
To ensure the whole trip isn't consumed with screen time, I'd take a timer for specified gaming time. What my sister does is give her kids rechargeable batteries. Once their juice is gone, you must wait until they're recharged. You can conveniently leave the car charger/adapter in the trunk ;)
We enjoy music, (name or animal) alphabet games, licence plate solving games and just talking about favorite summer moments on long trips. Always bring reading and puzzle books for quiet time. My kids also like reading the paper map we bring along. Navigation systems are cool, but they don't allow you to see where you've been. So as soon as my kids ask, "Are we there yet?" I pull out the map and let them solve the question themselves. They should be able to identify where you are at that moment by reading road signs, where you started and the final destination. Your boys are old enough to do that. If they have trouble, you're right there to teach!
I ask the kids for help preparing healthy snacks for the road. We make our own fun mix with pretzels, cereal, mini crackers, M&Ms, yogurt or plain raisins, etc. They get to pick their drinks at the store, sometimes asking for stuff I don't usually buy. We almost always pack sandwiches, so they have a say in what they will have when we stop to eat. My kids also get to choose a few pieces of fruit and wash/prep them as well. They have to feel like they're contributing, so making decisions helps that along.
My last suggestion is that you plan a fun stop or two along the way. That takes a little research, but there are always things to see on a 7 hr trip. It breaks up the road time, allows them to stretch their legs and makes a huge difference in behavior. For rest stops, bring a soccer ball or a frisbee. Have a great time! Take lots of pictures!