In Utah, difficult rated trails I have done bone stock in terms of suspension are Fins and Things (the entire trail, both loops, but not the optional stuff), Towers Arch, and Rainbow Terrace (recently upgraded to hard from moderate due to one spot). I did have 1" all around lift on Elephant Hill, Kamikaze, Boxcar. All the rest I have driven there is rated moderate or easy.

In AZ, other trails rated difficult I drove on stock suspension are Red Rock Powerline, House Mountain (sucks on stock suspension, very bumpy on top), and Crapshoot.

I have driven Diamondback Gulch in my Outback and I only had 1" lift and went up the big hill that the pink Jeeps only drive downhill.

Sedona trails are a good beginner's ride. They are nowhere like what Moab can throw at you.

As for the hard Sonoran area desert trails, I don't see the point. Those are only driven for the sport. So a toy is the appropriate vehicle. They offer no scenery that you cannot see from a trail any 4R can do.