Oh Yes Yes yes!
This was my first ever Nepal trek (about 18years ago now - gulp) and it was my favourite.
We went when there was a festival on, so we had to go the alternate route and it was quite difficult. We started at Chisapani then onto Kutumsang, Tharepati, Gosainkund (that was the hard part), Sin Gompa, Lama Hotel, Gora Tabela, Langtang, Kyangin Gompa, Langtang, and then back to Kathmandu via Dhunche.
From memory it was about 5weeks all up with a week in Kathmandu either side. An amazing trek, absolutely stunning. You can do the tea house trek which saves you carrying a lot of gear, or you can go with guides and camp like we did. about 6 years ago
There you can trek by two routes. One is as LisaF mentioned and another is starts from Dhunche/Syabru benshi then first trek to Kyanjing Gompa and finished at Syabru beshi. It's about Kathmandu to Kathmandu 9/10 days. and above LisaF itinerary takes about 2 weeks and better also.... It is totally tea house trek where you can get food and lodge for night. You do not organize camping/tent trek. But I recommend to hire a guide and porter from registered company... if you need more information, please do not hesitate to leave me private message....
Raju about 6 years ago