Hi,
Our parks have some nicely paved easy to navigate roads. These are there to make the park accessible to everyone. If you stick to these roads, you can still see a lot of the parks, as the routes are planned to take you by many of the major highlights.
There may be some roads where 4WD is required or recommended. Only a small portion of the visitors to the parks venture onto them. It is a good idea to know the conditions of these roads and have emergency supplies with you if you plan to go. From my experience, the 4WD is handy because of the high clearance of the vehicle. These rough roads generally are narrow dirt roads with giant potholes and deep tire ruts.
For more information on driving in each of those parks, visit the NPS site. www.nps.gov. For each park and monument you've listed, there should be a page about getting around.
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