Some special treks of nepal :

1. Annapurna base camp trek for 12 days.
2. Langtang gosaikunda trek for 12 days.
3. Everest base camp trek for 12 days.

Some famous short treks :

1. Poon hill trek for 5 days and two days for pokhara total seven days.
2. Langtang trek for 8 days.
3. Helambhu trek for 8 days.

Most of the people like to go trekking for one week and afterwards, visit chitwan national park for around 2 nights and 3 days to see the wild animals like rhinose, tigers and many more kinds of animals. Tourists love to do sightseeing as well in Kathmandu, Bhaktapur and Patan Durban square . Bhaktapur is on the list of the Unesco world heritages and really beautiful.
I recommend to stay two weeks in total in Nepal to enjoy our wonderful country. During the trek in Nepal trekkers will sleep in hostels every night.

Market square in Nepal Tempel in Nepal