Hal's typical male height though not tall. So maybe more like 5.9 - 5.10. Barry could be six feet.>>113831400
Karen has too much added to her with this and she's wearing a helmet but you can still tell she's shorter than Babs. There's not enough difference between Kara and Jess here.>>113831518
This image seems to do the different heights justice.
On a side note I remember years ago when I actually did give TTG a shot the show mentioned that teen Robin was actually 5.7 so so we know that despite exaggerated styles a character can be taller then they look.
My final guess:
Karen: 4.11 -5.0
Babs: 5.2- 5.3
Zee: 5.4 - 5.5 (stranded girl height i guess)
Jess: 5.7 - 5.8
Diana: 6.1 - 6.2 (she can't be taller without explaining the amazons and she needs to be taller to stand over most people.