There is essentially one road through Bhutan, which follows a series of mountains and valleys. Most travellers will follow this road from east to west, starting from Paro (the home of the country’s main international airport). How far along the road you travel, and how many mountains and valleys you visit will depend on the length of your trip or your preferred pace of travel.
Each valley has its own distinct character and most have excellent accommodation options. Paro, Thimphu, Punakha & Gangtey are most widely visited, and would most likely be considered the ‘core’ areas in a Bhutan holiday. To get further off-the-beaten-track, consider Bumthang (the far eastern, agriculturally rich valley from which you can actually fly one way back to Paro) or Haa, which is just one valley to the east of Paro but scarcely visited.
With its Himalayan terrain, Bhutan makes a brilliant destination for trekking. The country offers treks for all levels, from meandering walks to intensive challenges; simply tell your consultant your preferred level, and they will be happy to tailor your excursions to suit.
Bhutan can also be combined in a multi-centre holiday. There are connections with India (should you want to contract the frenetic and the zen). You could hop to Thailand if you are interested in the contrasts of Buddhism, or would like to add a beach stay to your trip (if beach if high priority, you could even combine with The Maldives).