I tried on a full Saga XXL suit, I don't know what one but it was all bright green if that helps. Anyway It wasn't a "big" XXL, just a little bigger than most baggy snowboard brands XL. Definitely less baggy than my Burton XXL. I'm 6'4 too and it would have wanted it bigger to be just nice and baggy. If you want it to be stupid baggy like is fashionable these days then no way is it big enough.
I agree the fit is a nice baggy fit, its not gonna fit like a tall jacket but its good if want it to be baggy but not look like a clown either. I'm 6'2 and comes to about mid thigh, I'm pretty sure the zipper is a 34inch.
Having said that I don't think there is any length difference between an XL but I would check for yourself.