I've taken 50 from east of Dodge City to Grand Junction. I don't know about on into Wichita (which is a big city, for Kansas). I do know traffic on US-54/400 gets dense from about Andover west to the International Airport. In Wichita, there is a section of that 54/400 where the speed limit drops sharply while it still looks like freeway, a trap that catches my Wichita daughter from time to time.
While I live along US-60, I don't use 60 to get to Wichita. Much of the section of 60 you would travel from US-77 is scenic highway through the Osage Nation, it is not necessarily good RV road, being rough in many places and having no shoulders along most of it, without even much grass verge between pavement and the quite deep drainage ditches.
US-60 does not look so bad right out of Ponca City, but it gets worse as you get into the hilly country east of Pawhuska. US-60 also sometimes gets clogged with slow moving oversize loads. Just now they are hauling wind generator parts to build wind farms outside Pawhuska, but I've also gotten stuck behind drilling rigs and other large pieces of oilfield service equipment.
Kansas has built much better two-lane roads than Oklahoma, and takes care of them. I usually travel US-77 down to US-166, using 166 to get east to where my need to go south finally puts me onto an Oklahoma highway, US-75 in my case for my trips to and from Wichita. US-75 actually is not too bad from Kansas to Tulsa, having been upgraded to four-lane divided in the 1990s, but it gets slow going through Dewey-Bartlesville because the developers have had forty years to build a whole new town on what used to be the Bartlesville bypass.
To get to Wagoner from Wichita, I would take I-35 down (or US-77 down from Augusta) to US-412 (Cimarron Turnpike) taking that all the way across to Tulsa, then out US-51 (Broken Arrow Expressway - Muskogee Turnpike) into Wagoner.
I know some people like to avoid the toll roads, but some of the routes that look like good alternatives (like US-60 from Ponca City across to US-69 down to Wagoner) are really bad alternatives either from road condition or the kind of traffic they carry.
If you really don't want to pay tolls, or go through Tulsa, you could take US-166 all the way to Chetopa, then US-59/OK-2 down to Vinita, where you can pick up US-69 south to Wagoner. Coffeyville will slow you down on 166, for about the same distance as Bartlesville slows US-75, but not as many traffic lights. US-69 has some four-lane sections, but even those have been pretty well beat up by the heavy truck traffic.
Along US-50, great places to visit include the Colorado National Monument, Gunnison (like a little Durango), Black Canyon National Park, the Curecanti National Recreation Area, Royal Gorge, and Bent's Fort NHP. US-50 basically follows the valley of the Gunnison River from Grand Junction to Monarch Pass, then the Arkansas valley into Kansas on the eastern side of the Rocky Mountains.
A little off the route we've discussed, I like to stop at the Henry Candy Factory in Dexter, Kansas. This family business is descended from the confectioner who created the O-Henry candy bar, and they are open every day, making candy on weekdays. You find Dexter by turning left off US-77 onto K-15/US-160, then following K-15 where 160 splits off.
