KOTOR (the first one) when you're on the planet before the Star Forge. You take a right fork near the very beginning of the level and come out on a viewpoint. Nothing else just an increible scene before you of the sea, distant island moutains, perfectly blue sky, a few crashed ships, bliss.
Standing on the top of the church in Damacus in Assassins creed and looking out over the city as the sun rose high in the sky. Good times.
Fallout 3, cresting the top of a hill/building and gazing around the scenery.
Photographing animals in Beyond Good and Evil.