When driving from Milwaukee to Los Angeles, we decided to take a small detour to see the Grand Canyon. The national park is located in Arizona, around a four hours drive from Las Vegas, and costs 25$ per car to enter. The entrance fee gives you a free information folder with a map and free parking at the Desert View, where you have a view over the Grand Canyon and the Colorado River.
The road between the Grand Canyon and Las Vegas goes through the Hoover Dam, which is a big American Landmark. Right after you cross the 221meter tall dam, there is a place where you can stop and take pictures of Lake Mead and or follow a guided tour inside the dam. We found the car ride on top of the dam was enough, and it gave us a great view over the construction and the lake.