Aron did a nice article a while back (can you believe I have to say "a while back") on how he would scout an area, initially with a spotting scope from a few miles away and then go to the areas that showed promise for a closer look. If you can find it, or if he remembers where it is that should help.
Also, if you can get into the terrain view on GE or GMaps you will be able to check the contours to see if there is a terrain feature that would block your view from your likely glassing location.
Too many what ifs in this scenario for someone to tell you how far away you can spot game.
I have some areas that I can glass game for 5 miles if not more and others were I can only glass 1 mile. The terrain, species being hunted, time of year, weather, heat mirage, glassing position all play a part in it.
Typically I try and get to a good glassing knob or spot and play it from there.
Sorry for being to vague. I'll be hunting elk and mule deer the last week of sept. in western wy. I have several vantage points picked out where I can see the faces of the surrounding mountains anywhere from 1-4 miles away. So my question is, will I be able to spot a deer or elk and be able to make out a shooter at those distances?
I would say yes for sure. Though it depends on what classifies an animal as a "shooter". If you're looking for a big mainframe and a mature deer then yes definitely. If you're going to pass up a buck because he's 175 and not 180", well then probably not at greater than 1-2 miles. Though you should be able to define if a deer/elk warrants a closer look from your selected vantage points!