IMO:
I don't know if Ennis would see any one particular spot, but Brokeback as a whole. This was their place, every stream, hill, mountain, pasture. Brokeback was their world, their country. There was no where they couldn't go. No where they couldn't sit and get drunk, smoke a little pot, jump off a clift into a river, no where they couldn't make love. The only place where they were truly be themselves.
Ennis, I could see standing on hill over looking a stream, letting Jack ashes just go all over, everwhere. So no matter where he rode his horse on Brokeback Mountain Jack would alway be there, riding with him.