Lotschberg Tunnel

It all comes to the season you are travelling. If you are going from June onwards, I'd go around via Guttanen and Oberwald (passing through the amazing Grimel Pass 2.700m high). It is a ride not to forget, one that is above any mountain train experience you will ever have in Switzerland. If you are going when that pass is closed (late October - June), then you can use the train shuttle. There is not much traffic there to cause long queues. Shuttle takes 15 minutes to cross the tunnel and it costs CHF 20 (25 weekends) I know some train fans will come here and tell you "it is not worth the hassle" and that you should go by passenger train all the way. I'll disagree in advance: Valais is very beautiful, and even if you can't reach Zermatt itself (have to take a cog railway for the last 5km) all the rest will be worth the trip. If you have ever driven in winter conditions in US, you should have no problem managing it. Just pay utter attention to speed limits, enforcement is tight in Switzerland.

We will be traveling June 11.

We have only been to Zermatt (underwhelmed but nice, the train into town is a non-event) by train. We have used the Lotschberg Tunnel but only to go to Italy. The Lotschberg Tunnel was interesting for one go but I wouldn't likely go that way again. Whereas many of the other shuttles in Europe are closed the Lotschberg one is open frame so there is not much between you and the tunnel walls. No language barrier at all. (as I said, not much barrier at all). In early June our wait time was 20 minutes - YMMV - and about 10 to load and dispatch. Off loading took about 10 minutes too. Another thing we didn't like is on the Italian side all the roads are very tight and winding and are now absolutely full of a train's worth of trucks and cars so that bit of the drive was slow and unpleasant. Would you feel the same going to Zermatt? Dunno.

Zermatt was also underwhelming for my family. After spending time near Interlaken in the Lauterbrunnen Valley and the mountain villages Zermatt was just WAYYYY too touristy for us.