They run smaller than you might think. They're the regular fit ones from last year right?
I ordered a pair of those last year in L (I'm 6'), and they were way too small for me, so I sent them back for some L Pieced Togethers (baggy fit), and they're a good, standard, slightly baggy fit. Not even close to as big as my saga's though.
So, point of the story is that you'll be better in the bigger size, and if you want those to be pretty baggy you'll want XL at least.