The 29" fell really great on the Levo, I went with the Santa Cruz Reserve 29er 30mm, DT Swiss hub with Butcher 2.6..I am in Austin Texas and it just rolls over almost anything. I am on the taller side as well (6'4") and am much more comfortable on 29" wheels...
I am 6'4" and I went with the XL and am totally comfortable. I have a dropper post and 29" wheels. If possible I would honestly try before you buy, I was on the fence for a long time about the XL until I tried it.