So much to tell, so little time! Your timing is perfect. Last year we drove east across southern Utah and back across northern Arizona for two weeks starting Memorial Day. The high desert was in full bloom. Prickly Pear Cactus, Sage and many other flowers we in bloom. If there has been any rain this winter you should get a great show. We called our trip "Rocks and Rock Art" because we were there to see the colorful Utah Rocks, and some of the most important and beautiful Rock Art in North America. Since you have already done your research here are a few special sights you might like to explore.
BTW, An all wheel drive vehicle will expand your options significantly and make most washboardy gravel roads more comfortable.
Zion NP has some of the most interesting and beautiful day hikes of any national park. Look into Angels Landing trail. Also look into Kolob Canyon Scenic Road which leads from Virgin to Cedar City through the northern part of Zion NP.
Take a side trip to Parowan Gap (1/2 hr northwest of Cedar City) to see some very elaborate petroglyphs, including an astrolabe.
Bryce is unique and has several short day hikes that get you down into the colorful hoodoos.
Cedar Breaks National Monument is a "mini-Bryce" and worth a drive through.
Red Canyon (along Rt 12 west of Bryce) is a colorful lunch stop.
The drive east along Rt 12 from Bryce is beautiful but don't just follow the highway. The entire area between Bryce and Capital Reefs is called the Grand Staircase / Escalante National Monument. There is a Visitors Center in Cannonville. On the western side of the Monument, south of Cannonville, you can walk through slot canyons, visit Grosvenor Arch (a huge triple arch), and drive scenic Cottonwood Canyon Road (be careful, there are lots of Cottonwood Canyons in the southwest)
Further along Rt 12, still in GS/ENM, you can take "Hole-in-the-Rock" road south of Escalante, a 78 mile mostly easy gravel road to the hole-in-rock where the Mormon settlers had to lower their wagons to the Colorado River by rope. It is now a gorgeous view point overlooking Lake Powell. The last 5 miles are over some small rock ledges but our rental Jeep Liberty had no problem at all but low clearance vehicles left lots of metal scrapings on the ledges. The surprise was the desert bloom. Dense bunches of blue and purple sage flowers made the desert floor almost glow as we drove the route. This road is another Utah rock playground with strange rock formations (Devil's Garden), slot canyons with colorful names like "Spooky" and "Peek a Boo".
Most people just tour the Rt 12 portion of Capital Reefs National Park but this park is there mostly because it protects one of the most beautiful (if you are a rock fan) geological structures in the Southwest, the Waterpocket Fold. It's another long ride south from the highway. There is also a northern section called Cathedral Valley, again a gravel road trip, this time with stream crossing, that has some spectacular thin rock spires sticking up in the middle of a valley.
Some of the best Rock Art in the southwest is in Sego Canyon, just north of I-70 near Moab and in Horseshoe Canyon, south of Green River, UT. Horseshoe is part of Canyonlands NP but physically separate. It contains some of the oldest and most beautiful art galleries in North America. It takes a 7 mile round trip canyon hike to see them but they are stunning. I took this
wide-angle multi-image shot of the Great Gallery last year. The best way to view the image is to expand it vertically and then scroll sideways. These paintings are believed to be between 1 and 3 thousand years old.
Of course the main part of Canyonlands is well worth a visit. Think about taking Shafer Canyon Road from the Park to Moab. It is a good quality gravel and rock ledge road but it is a cliff hanger. If anyone in you party is not comfortable looking out of the car window at vertical drop offs, skip it. You can get a look at the road from the Viewpoint just opposite the Main Visitors Center.
Arches NP is also fascinating but don't forget to take a drive to the Needles part of Canyonlands NP, south of Moab.
We returned to Las Vegas by traveling south to Arizona, via Natural Bridges Nat Mon, the Moqui Dugway (lots of spellings for this one), Monument Valley, Antelope Canyon (a Navaho run slot canyon tour of a very narrow and colorful slot canyon in Page, Az), and the North Rim of the Grand Canyon. We like the North Rim because it is much less crowded and more intimate than the south rim but there are also fewer facilities so it is harder to stay nearby. The few lodges are booked early.
You can Google many of the placenames above to get more info. If you are a Google Earth fan, I have GE files for Southern Utah and Northern Arizona Points of Interest, also a large file showing rock art locations in the southwest, and a file showing ancient ruins in the southwest. Send me a private message with an email and I can send them to you. I also have them in Garmin POI format.
PS, also look into the scenic Burr Trail into Capitial Reefs from Escalante
PPS, this is far and away the
best site for preparing for a trip to the American Southwest
.