I'm 6'4, right now I'm wearing an element plain tee, size large, and it fits very well, and is quite long yet slim. Personally I like a slimmer fitting tee, you can find them at like boutique skateboard, snowboard kind of shops. Just look for slim fit tees in a large or xlarge wherever you go.
Now the real problem is, who has feet over size 14, that is the real problem.