I'd save them or set them up for stabilizing Swales and terraces on steeper slopes. They might also act as a slow drain for your Swales so pick their location carefully. And I second the microclimate idea!
You may find, as I have that you can move larger rocks with the bucket of your tractor by skidding them. Just push the bucket under them to reduce friction and gain control then push them without lifting.
And in my experience you can't gain much by selling rocks. If you have them so do those nearby. The value is in trucking them long distance, not a big help to you. On our farm we have just piled them for decades in an easy to reach location (ie not in a ditch:) for use later. They were traditionally used as boundaries. We have two hundred year old rock boundary walls long after the generations have forgotten where the line was.
Happy stacking!
