Don't know where in AZ you are starting out--if you travel north of Phoenix, there is 1 really tough, long pull going to Flag.
I-40 from Flag is not too bad as I remember, but there are also some long pulls, but not tough.
I have just recently traveled I-10 from Baton Rouge to Lafayette--very rough.
Also recently I-30 DFW to Shreveport, very nice.
Also recently I-40 Little Rock to Memphis--some very rough areas and also construction.
Not sure if this helps, but just about any where you mention but TX, the roads tend to be tough on RVs--not that there aren't some bad areas in TX, just not the norm.
I find myself traveling a lot in the passing lanes just to avoid the semi ruts and potholes, but try to move right when I note traffic gaining on me.
Takes a lot of attention to what is just ahead to keep from having a severe jolt...
2016 Tiffin 40 QBH
2015 38RSSA, traded
2005 TK3 #1869, 10 yrs of memories,
2017 F450 KR--one more Ford is it
2009 F450 4x4-died; 2010 F450-retired