Bar height - for those of us who are fatboys - helps the back strain. The first shelf underneath should be only a foot or so from the top so that it can be used for fast storage - army trays, dead models, dice, bins, ect - like the sideboard. Then the larger amount of space below would be for a shelf just off the ground for terrain and the like, of course...

Oh - padded corners and edges, like a billard table.