A varied trek, landscape, vegetation, and culture all change constantly. There are  numerous fascinating villages. The chief difficulty is that after several steady days in the Marsyandi valley you reach Manang at 3400 metres, and a couple of days later you are 2000 metres higher on the Thorung La. Be aware of the potential for altitude-related problems.

Things change ! Road-building is going on apace both up the Marsyandi Valley towards Tal (and ultimately, at some future date, to Manang). In the Kali Gandaki valley it's now possible to reach Muktinath by jeep via Pokhara - Beni - Jomson. Buses run from Pokhara to Jomson (and back !). It's debatable how this road building will affect trekking. It makes it feasible to do the shorter Circuit, for example Besisahar to Jomson, in far fewer days, but presumably trekking and traffic are not such a pleasant mixture. A relatively new option is to rent a mountainbike in Muktinath or Jomsom and ride your way down, turning road construction in a positive thing for tourism. Mustang is on it's way to becoming a major downhill biking destination. 

There are numerous lodges along the route, some of them very good.

Day 1: By road to Besisahar

Day 2: Trek to Bhulbule (if you arrive in Besisahar early, or the road has now been pushed further, you could get to Bhulbule on day 1)

Day 3: Trek to Syange

Day 4: Trek to Tal

Day 5: Trek to Latamrang

Day 6: Trek to Bhratang

Day 7: Trek to Bragga (or Manang)

Day 8: Rest / acclimatisation

Day 9: Trek to Lettar

Day 10: Trek to Thorung Phedi

Day 11: Cross Thorung La to Muktinath - the big day, reaching 5400 metres at the summit of the pass

Day 12: Trek to Jomson

Day 13: Trek to Kalopani

Day 14: Trek to Tatopani

Day 15: Trek to Chitre

Day 16: Trek via Ghorepani to Ullieri

Day 17: Trek to Birethanti

Day 18: 30 minute trek to Nyapul, then bus or taxi to Pokhara

Add one spare day to be taken when you want it during the trek - particularly if you have acclimatisation concerns at Lettar
 

Shortening the trek:

It is possible to fly, or to go by road, from Jomson to Pokhara  (brings it down to 13 days)

From Tatopani you can continue down the valley to reach the road at Beni then drive to Pokhara on Day 15

 

 

Additional Info

downloadable map:

http://howadoor.umbra.cz/img/map/Anna...

1)  Avoiding the worst of the new Roads

http://www.nepal-dia.de/Trekking_the_...

Above being new downloadable guidebook on recently opened trails

http://members.virtualtourist.com/m/p...

Above a trekker's personal experiences including route descriptions and photos of the new roads

2) Guide to minimising the chances of being adversely affected by AMS

http://www.ismmed.org/index.php/preve...

Above info provided by The International Society for Mountain Medicine