[Messianic]

You could probably do big chunks of Sol A, if you're careful and fairly twinked...And Sol A is pretty good exp, still. I wish I could remember what I did on my monk between 30 and 40...that level range is such a blank in my memory (10+ years ago).

I spent a crapton of time in lower guk though - once you're about 33/34 you can probably handle the entrance mob spawns (the initial spawn, the two down the ramp, and all the mobs on the left, including the ghoul roamer, the two solo spawns, and the three together spawns in the room next to the waterfall).

There's another ghoul spawn on the right, but i don't recommend that side because of really annoying caster mobs. Keep pumice on you...

You can also do live side, which is heavily neglected yet really good exp, particularly 40+ solo (minos, etc).