Travel to Biel / Bienne. Take the train to Twann, Ligerz or Cressier (towards Neuchatel), hike up to Chasseral which is at 1609 meters.
The Twann Schlucht is a very beautiful gorge.
Stay in chalet style hotel,
http://www.chasseral-hotel.ch/ at Chasseral mountain top. They
do not take credit cards!
Next day hike down the other side to St Imier. Take train back to Biel.
Total hike is only 30 Km, but rather hilly! There is a sporadic Post Bus on the south side.