Thanks for that!
We're investigating a B&B on lake Thun. We're planning on doing a couple of boat trips (they do a BBQ night on one of the boats) but I didn't realise there were trips into the mountains! So thanks for that! We may have to spend another day there!
We're doing a road trip from Calais down to Bern. Making some stops along the way there and back. We're still sorting out our plan.
We were planning on staying in Bern but it is, like you say, very expensive. We like beautiful cities and scenery and when we saw lake Thun it won out over Bern. We may still stop in it though.
Our other plans are to go to Luxembourg on the way down and Reims (champagne country) on the way back. Other possible stops are Dijon and Strasbourg.