How the country fits together
Almost everything a first visit covers lies in the west. Paro, Thimphu and Punakha sit within a few hours of one another, separated by passes at around 3,000 metres. Head east and the drives lengthen quickly — Bumthang is a long day from Punakha, and the far east another two beyond that.
There is no railway. Domestic flights exist but are few and weather-dependent. So the arithmetic is simple and worth understanding before you plan: the further east you go, the more days you need — and the fewer other travellers you will meet.
Our advice, almost always, is to go slower rather than further. Three valleys properly is better than six from a car window.