We drove to Interlaken a few years back. Stopped over in Paris and stayed just outside on the SE side overnight. Didn't touch a toll road to Interlaken - not for reasons of cost necessarily, we just thought we'd take it easy and do the more scenic route. Surprised to get there is very good time, no problem at all. Switzerland - in the mountains - is absolutely fantastic in the Summer. A rail ticket gets you every single train, funicular, cable car, the lot - except the big one, the Schilthorn, you have to pay extra for that. You can get all around the mountains in every direction. Fabulous views of the meadows and wild flowers.