If you're looking for a city to take a break in while you're cruising around the southwest USA in search of some vacation adventure, Flagstaff should fit the bill!
Unlike some of the other cities in the area, Flagstaff is relatively cool and right in the middle of the largest forest of Ponderosa Pine in the world. That will give you a totally different hiking experience if you've been out and about in the rocky desert.
You can also see a little bit of some American history where the iconic Route 66 used to pass through Flagstaff. There isn't an official "Route 66" anymore, but you can still check out one of the most famous stretches of road. It's still called Route 66 in town, as a street name. 
One particularly famous site in Flagstaff is the Lowell Observatory, where Pluto (now considered a dwarf planet) was first discovered in 1930. Today, visitors can learn more about the observatory, and enjoy a little star-gazing at night.
Outside of Flagstaff, there are several major parks that you should plan on visiting. The most notable is the Grand Canyon National Park, which needs no introduction. It's about 75 miles away from Flagstaff and an easy drive by car or RV to get there from the city. There, you can see one of the most spectacular natural sights in the world and of course hiking and Jeep tours are everywhere.
Other parks you might want to check out are the Sunset Crater Volcano National Monument, Walnut Canyon National Monument 
and Lake Powell. A little closer to the city is Mount Elden, where you can do some hiking or rock climbing. During the winter months, you can head up the San Francisco Mountains to the Snowbowl ski resort and have some fun in the snow.
Quick Facts:
-- In the movie "Forrest Gump", Forrest runs through the streets of Flagstaff during one of his cross-country runs.
