Dang GP...that's looking awesome! When I was reading the text of yoru post I was goign to say it seems like you might be just doing a map and not focusing on the symbols...but the way you've put this together I can totally see how the symbols can be pulled out.

And this also proves that for most western themed maps (focusing on art as opposed to functionality) the resolution doesn't need to be very high for the symbols. But knowing you GP there will end up being some hi-res stuff in here.