We are trying to plan a trip with our two kids (who will be 10 and 12 at the time of this trip). We will be flying in to somewhere from NJ and would like to see some sights like Yellowstone, Grand Tetons, Mesa Verde National Park and the Grand Canyon. We have gotten lots of suggestions regarding other places (such as Carlsbad Caverns or Mount Rushmore.) We will take about 15 days for this trip. Any suggestions about where to start and what places to see in that time frame? Thanks for your feedback!