Hi DAS26miles! Coincidentally, I live in Sedona and grew up in the SFV!
You can drive to Sedona via I-10 through the Phoenix area or I-40 through Flagstaff. Both ways are about the same time and mileage. Either way, get on I-17 then take exit #298 (Hwy 179) to Sedona. Yes, there are several roundabouts along Hwy 179, but no problem with my motorhome, so you certainly should have no problem driving through them.
mileshuff is referring to Hwy 89A (not 89) between Sedona and Flagstaff, aka Oak Creek Canyon. Beautiful drive. That's another way to get between the two towns (alternate to I-17 and 179). There are about 2 miles of switchbacks to ascend/descend the canyon. Otherwise it is several miles on the canyon floor alongside the creek. We used to drive it in our previous 23' Class C, but don't drive it with our current bigger motorhome. Sort of narrow with trees and rock walls along the road. So if you are experienced and comfortable, you actually could drive it with your RV. But the easier route would be I-17 and 179.
When is your trip? Try to arrive before dark to see the scenery as well as to avoid critters (or big critters!) that may be on the road.
Rancho Sedona RV Park is a nice park, naturally wooded and by the creek. Look at their website. Right on the front page, it says they are dog friendly!...as long as you follow the rules.
If you drive in on Hwy 179, stop at the Ranger Station Visitors Center at the south end of town (if it's not too late) to get lots of info.
I would plan a second night in Sedona, especially since you will be arriving late in the day. Hike/walk on one or two of the many trails. You can park your motorhome at several of the trailheads, most noteably along Hwy 179. You might want to take the Sedona Trolley Tour and/or a Jeep Tour. Visit Red Rock Crossing, a great place to picnic with iconic Cathedral Rock (you've probably seen photos) by the creek.
Enjoy your trip!