Volcanoes National Park
The headline park, on the slopes of the Virunga volcanoes in the country's northwest. Twelve habituated gorilla families, golden monkey trekking as a side activity, the Dian Fossey grave hike for those wanting more time on the mountain. A small group of conservation-led lodges sits directly on the park's edge, each within driving distance of the trekking start. Three nights is right.