Depending on your route, the Lötschberg may or may not make sense. It certainly makes sense if you're going over the Brünig afterwards to Luzern. But if you're driving to Bern or further to Basel, it can be a lot faster just to drive around. In Kandersteg, the trip up the gondola (and short hike afterwards) to Oeschinensee is a highlight. Also worth a visit is Blausee, just further down the valley. It all depends on how quickly you are trying to transit.