The Paro valley is small and most sights are accessed by car from a hotel base. Tour operators provide a vehicle and driver as part of the standard Bhutan package, so you won't be navigating yourself. The main road runs the length of the valley with Drukgyal Dzong at the north end, the airport in the middle, and the dzong, museum, and town clustered around the river.
Paro town itself is compact — a few blocks of two-storey painted buildings around a single main street, walkable end to end in fifteen minutes. The Tiger's Nest trail starts at a car park ten kilometres north of town and is the one place where serious walking is unavoidable. For the rest, even the temples can be reached within a few minutes of getting out of the car.