Just N of Flagstaff, I would recommend taking the loop thru Sunset Crater and Wupatki Natl. Monuments. Sunset is a fascinating volcanic area that used to have some 4wd trails in years past and Wupatki has numerous ancient ruins one should not miss. Walnut Canyon just east of Flagstaff also has a beautiful trail thru ancient ruins. Navajo Natl. Monument along Hy 160 east of the Grand Canyon has a great ruins N of Kayenta, AZ lies Monument Valley with an easy but beautiful loop thru the Navajo Tribal Park within. Along this Hy 163 N of Kayyenta lie lots of old volcanic spires. Just N of Mexican Hat, UT lies Valley of the Gods with a very scenic easy loop road that you could take from either the E or W sides. Great loop with some great camping spots. The Goosenecks Of the San Juan state park is nearby too. There is a scenic 4wd trail that leaves off the Highway leading into the Goosenecks park that goes for miles to the west along the N rim of the San Juan River that is scenic, remote, and has good camping spots. I also recommend Elephant Hill in the Needles area of Canyonlands. Great trail leading S off the Elephant Hill main trail that you can take all the way into Beef Basin where there are numerous Anasazi ruins. Very remote with good camping. You really can't go wrong anywhere in S. Utah. As others stated, the White Rim is great but long but you need campsite reservations which are hard to come by this time of year. The Dark Canyon area is great as other have stated.