Again, she's been depicted as taller and shorter depending on the source. In New Frontier, she was incredibly tall, easily taller than Superman even. In New 52, she's about half a head shorter than Batman. Alex Ross also seems to draw her about half a head shorter than Bats. For the Justice League animated series, she's almost a full head shorter than Batman.
Now, Affleck is 6'4". This Gadot gal is 5'9". That's a difference of only 7 inches. This is about the height difference I would expect between Batman and Wonder Woman, so long as they don't go the non-standard route that New Frontier did. And if the production wants to close the gap at all, it's not hard. Look at the height disparity between Bale and Hardy, then watch The Dark Knight Rises and see if that shows at all in the film.
ps I'm hoping for a headband instead of tiara. Like the concept art by Kris Anka posted earlier in the thread.