How can I liven up run-of-the-mill stir fry?
I notice you didn't mention fresh ginger. That's a very distinctive flavor addition that is commonly used in stir fries.

Also, don't know if this counts as a "major addition" [that you aren't asking for], but since you do mention veggies: bok choy, "baby" bok choy (which I think is a different plant from "adult" bok choy), or mustard greens seem like innocuous vegetables but really punch up the cruciferous flavor in a dramatic way. (especially the mustard greens)