Grand Canyon to Zion

'Steep' downhill grade into Hurricane. 55 to 45 to 35mph. The highway drops you right into a residential zone. It isn't a big deal though, plenty of loaded semis doing the same thing.

Climbs? North toward Page you have 'The Big Cut' just north of Bitter Springs. There is a passing lane the whole way up so take your time if needed. Then as you get closer to Page you have '12 Mile Hill' which is a short downhill with some curves; not even sure if it is worth mentioning, other than just watch the caution signs for speed.

I cannot think of anything else for that particular route for going to the West Entrance of Zion's.

If you were to choose the East Entrance however, a few miles north out of Kanab has a not steep but few mile long climb. It is quickly followed by a long sweeping curve downgrade into Mt Carmel Junction.

For any of the above, your Winne is plenty capable. Every grade I've mentioned is considered a normal route for over the road trucks. You are over thinking this.

maybe I am over thinking my 29 foot Winnebago MH.

Switch backs coming from US-89 into Zion is one of the reasons certain sized rigs are not allowed. Dropping into the canyon has several switchbacks where many rigs drag.
Steep grade for some is northbound south of Page.
Fredonia to Hurricane on AZ 389/UT 59 has some advantage. I haven't been that way in many years.
OP does not indicate what kind of rig and how long. This could help

I am driving a 29 foot Winnebago class c. I am thinking 89 to 389 to 59 may be doable if steep grades are not too long. Does anyone recall if there are any long steep grades down on this route?

There's a simple way and very scenic. If you're staying in Grand Canyon South Rim then exit via Hwy 64 east to Hwy 89 at Cameron. Take Hwy 89 north to Page, AZ and continue on 89 West to Kanab, Utah. This would be a good stop to tour Best Friends Animal Sanctuary if you're an animal lover. It's a no kill facility in awesome surroundings and you won't find anything similar.

From Kanab, Ut. take 89 south a little way into Arizona at Fredonia, AZ. Then take 389 west which becomes 59 in Utah to Hwy 9 in Utah at Hurricane. (This part of Hwy 9 is just about flat.) Then either find a park on east Hwy 9 all the way to Springdale or stay in the park at Watchman campground. If staying in Springdale the park's free shuttle stops at various places in this small town.

You didn't say where you're heading after Zion but I'd recommend Bryce Nat'l Park. To get there backtrack on Hwy 9 west to I-15 and head north to Hwy 20. Take that east to Hwy 89 and go a little south to Hwy 12 taking you to Bryce. Stay in the park or just outside the park entrance at Ruby's RV. Hwy 12 from 89 to Bryce is again, just about flat. Hwy 12 from Bryce to Torrey? You probably won't like it although many, including us, do. :) However, if you want to get to Torrey to tour Capitol Reef Nat'l Park there's an easy way - from 12 take 22 north to 62 to 24 east to Torrey. Lovely drive.

When leaving Zion you don't want to take Hwy 9 east to 89. That's a big climb with switchback leading you through the tunnels. You won't like it!

All of the above are very doable with an RV with no major climbs or switchbacks. It's the easiest route. Have a great trip! By the time you do these parks you'll be a pro.

Oh as for Hwy 9 into Zion, likewise I don't recall any major grades or switch-backs. The one problem is the tunnel for which you may have to have an escort depending on the size of your RV.

I took 89 last summer with a Toyota RV w/22Re engine. Nothing too steep or scary.

enblethen wrote:
Only real way to avoid hills and crooked road is the long way around.
I-40 to Kingman, north on US 93 to Las Vegas then north on I-15 to Utah 9 into Zion.

Yeah the extremely long way around. I don't recall any major grades on US 89 which is the normal route and the one you have to take to get to I-40 anyway. But I am insensitive to anything other than extreme grades.

Only real way to avoid hills and crooked road is the long way around.
I-40 to Kingman, north on US 93 to Las Vegas then north on I-15 to Utah 9 into Zion.