Dick, thanks for the detailed insights on the AP settings.  I'll start paying closer attention to its effects.  It really does make sense though to follow a standard size though and if real world works as well as any, then it would make sense to use that.

One thing I've noticed myself while out in the desert is that size can be very deceptive.  You can see a hill that looks gigantic but then when you get close its really not so large.  And vice versa.  I've only noticed this "mirage" in the deserts, not in the forested North West.  I'm not sure why.  Maybe it was just me getting disoriented in the heat?  And when I lived in LA just two blocks from the mountains, there were MANY days when we couldn't even see the mountains at all due to the high "Aerial Perspective" setting.  I've heard the smog is better these days though.