The reason for reversing your direction of travel is specifically to make the best use of your drive on the Pacific Coast Highway. Driving south on this road from Monterey to San Diego will put the ocean on 'your' side of the highway making it much easier to pull off and get back on the highway, especially for spur-of-the-moment stops such as when you happen to notice a sea lion rookery. Otherwise, there's usually not a good reason to drive a loop in one direction rather than another - that's one of the beauties of a loop trip.
And as you plan your trip, in whichever direction you choose to go, here are a few other spots along the way that you might want to check out. Between San Diego and Sedona: Anza-Borrego Desert State Park, Yuma Territorial Prison State Historical Park, the Heard Museum. Around Sedona: The town of Jerome, Tuzigoot National Monument, Oak Creek Canyon. Between Sedona and Monterey: The Grand Canyon, a long stretch of old Route 66, London Bridge, Mojave National Preserve, Pinnacles National Monument.
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