From another post it sounds like you're coming from Idaho so here is a route we'd suggest:
I-15 south to Hwy 28 at Nephi (south of Salt Lake City) to I-70 east.
I-70 east to UT 191 south to Moab and Arches. Many RV parks in the area. You can also easily check out Canyonlands from Moab.
From Moab, North to I-70 and west a short distance to Hwy 24. South to Torrey and stay here to check out Capitol Reef Nat'l Park.
From Torrey take Hwy 12 to Bryce (Ruby's RV is convenient). From Bryce take Hwy 12 west to 89. Now you have some choices:
If you don't want to take the Zion tunnel or can't because of the RV size, then take Hwy 89 north a short distance to Hwy 20 west to I-15. Don't take Hwy 14 across to I-15. It's steep, narrow and curvy.
Take I-15 south to Hwy 9 just north of St. George and east to Springdale and stay there for Zion. The free shuttle has its route in town and it's a pleasant place to stay. Or you can stay in the park at Watchman c.g. with electric, water fill and dump station. All easy driving.
The alternative after leaving Bryce and if you choose to take the tunnel is Hwy 12 to Hwy 89 south and Hwy 9 through the tunnel and into Zion. You should read this information on the tunnel before deciding. There are RV length restrictions.
Zion Tunnel InformationOr another choice is Hwy 12 to 89 south and stay at a RV park on 89 at Glendale or Mt. Carmel. Then you'd drive your tow vehicle through the tunnel for Zion. You'll have to take the shuttle for touring Zion. You can't drive your vehicle.
Exit Zion either by the tunnel and Hwy 9 east to 89 south.
Or...if you're in Springdale, take Hwy 9 west to Hurricane and pick up UT59 which becomes AZ389 taking you to Fredonia, AZ and Kanab, UT.
Stay in Kanab if you want to do the Grand Canyon North Rim, watch your timing because the park buildings and campground usually close mid-October. You'll have to check. The roads will be open though until snow closes Hwy 64 into the North Rim so you can still go into the park. The aspen will be changing color beginning around Oct 1-15 and it's gorgeous. Personally, if you're planning on the South Rim, also, I would skip the North Rim.
So, from Kanab, UT you can take 89 east to Page, AZ (the easiest) and out of Page pick up the Hwy 89 detour which has been in effect for about a year because of the 89 road collaspe. The detour might be shown on some maps as IR20. There will be signage directing you and it's now the truck route, too. It's newly paved and runs approximately parallel to 89. It's good for RVs and will bring you out to 89 south of Page.
From Kanab, UT another route is taking 89A through Jacob Lake and east to pick up 89. This is a very scenic route but you'll have a steep, curvy downhill a short distance from Jacob Lake. We've done it often but wanted to alert you - depends on your vehicle and your calmness
🙂So..now whichever route you take you're on Hwy 89 heading south toward Flagstaff, AZ. To work in Grand Canyon South, pick up Hwy 64 west off 89 which will take you into the park. This is just north of Cameron on 89. Stay at Trailer Village in the park itself if you can get reservations. It's the best and easiest way to tour the park as the free shuttle stops right at the RV park - full hookups.
Exiting the South Rim, take Hwy 64 south to 180 into Flagstaff and then pick up I-17 south to tour Sedona. Don't take 89A into Sedona if you have a big rig - steep and curvy. There are some RV parks around I-17 or Sedona itself (expensive). We feel Sedona is a zoo to drive a RV in so we always stay at Cottonwood in Dead Horse Ranch State Park (good for big rigs). You can then easily drive your tow vehicle into Sedona.
Heading home, get back to I-17 north to Flagstaff and east on I-40.
Sounds confusing but get good maps and you'll figure it out. Have a great trip!
For RV parks/campgrounds in the different areas of Utah and Arizona you might want to consult this site:
RV Park Reviews
Full-Timed for 16 Years
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Traveled 8 yr in a 40' 2004 Newmar Dutch Star Motorhome
& 8 yr in a 33' Travel Supreme 5th Wheel