I like the idea of a D-ring... I think I've seen some bags on Etsy where a stitch counter is attached to a D-ring by a loop of ribbon or something.

I think it would be better to have a matching zippered bag for stitch markers and scissors and stuff to prevent unexpected spills or stabbening (I keep mine in the penguin pouch you made me! but a smaller zippered pouch would work well for stitch markers). I voted against a velcro-closure pocket because velcro + knitting = a scary combination.