My husband has ordered from American Tall and had a good experience! He also regularly shops at Old Navy, Gap, A&F and Express for tall clothes. He’s 6’5” and has a 30” waist so it’s a constant struggle.
I had this same issue - my DS is 6'4" and thin. Hollister offers their joggers in a tall size online. They're a Christmas gift, so I don't know if they will fit him yet, but I'm hopeful.
(Also if you sign up for their rewards program, you get $10 off a $40 purchase!)