Thanks for the comments, Norm. Bright lighting is key to show different heights (Not that I'm an expert though, but I do have to, in the words of Peter Kay, put the "big" light on). I also use the different flock effects on the hexes for differentiating height, too. I use the plain flock for hilltops, and the mixed flock hexes for the lower ground. Seems to work, and anything to help the old dodgy eyesight, the better.
Best wishes