I'll bite, what is your rifle chambered in and what are you currently using for optics? First scopes that come to mind are S&B, USO, NF, PR, and March. Without knowing what you're shooting it's a crap shoot trying to help you find the proper set up.
Hunt up one of the websites which caters to the .50 BMG guys and ask what they use.
Or gear up with whatever the military sniper guys use...
Looking out my window at various objects at a mile and a half, I can't actually see a person-sized object without some sort of binoculars or telescope. If the target would be a house or a car, an old Weaver K4 would work as good as anything.