What to pack on a long road trip?

So we're going to start from Seattle, WA to Disneyland, no stops to sleep in between. It's gonna take one day to get there. We're gonna stay there for about 2 days then we're gonna go to Las Vegas and stay there for 2 days. Then we're going to drive back to washington from there and overall the whole trip is going to be about a week long. What should I pack? I only have one duffel bag for all of my stuff, and also what should we pack to keep in the car and for entertainment? Thanks (: