Pakse's Big Buddha sits on the hill at Wat Phou Salao, watching over the Mekong side of town. The statue itself is simple, but the setting is excellent: a terrace view over the river, bridges, low hills, and the spread-out city below.
It is best near sunset, when the heat drops and the river catches the light. You can drive or climb the long stairway; either way, treat it as an active religious site and keep shoulders and knees covered.