My only suggestion is that since everything is done in elevated view then maybe the coast line and river banks of the river look top down. How about thickening up on the vertical bits - i.e. the top line of the horizontal river therefore showing the river bank on that side. There was a really great map done a while ago by a chap on these boards as well as on RPGMapShare where there was a region all done in elevation where all the hills and valleys folded into one another. Cant remember enough to search for it now tho. It was a bit exaggerated for artistic purposes but it looked great.