I recently went on a long road trip that covered 3,700 miles in total. I used Waze for navigation because it's the best.....but I have a couple ideas for you.
1. Allow the user to type in how miles they would like to drive before stopping. For instance if I want to stop to get gas or eat at around the 240 mile mark of my trip, waze could then show me what is at exits in that vicinity (gas stations, restaurants, hotels, shopping, etc). I stopped once to have a cruddy gas station when two exits later there were tons of choices.
2. Suggest breaks. My car does this after I have been straight driving for 3 hours. What if Waze suggested the next Rest Area or something?