Well within driving distance of the hotels on the strip is the Grand Canyon, and many companies offer day trips from the city so that you can take photographs and gawp at the views. It's easy to dismiss the canyon, as no more than a big hole in the ground - until you actually visit, that's when you see the incredible views. The best thing to do is to drive out there yourself, and find a quiet spot and just sit down.
There are tons of hiking trails, and even helicopter tours that will take you down to the bottom - around a mile in some places!
