Which train route to get to Interlaken?

The quickest way from Zürich to Interlaken would be via Bern. The route from Basel goes through Bern, too. But if you go from Zürich to Luzern and then take the GoldenPass route on the cog rail train over Brunig Pass to Interlaken, it won't be fast, but it will be scenic.

Thanks! It looks like Lucerne is a better place to visit than either Basel or Zurich so we're considering flying to Zurich then immediately hopping on a train to Lucerne.

It won't make any difference if you go the fast route.

Basel - Olten - Bern - Thun - Spiez - Interlaken.

Interlaken Ost for going up to the mountains. Interlaken West (mostly) for staying in Interlaken (but I would stay up the hill).

or

Zurich - Olten - Bern - Thun - Spiez - Interlaken.

See the similarity?

Both entirely on the flat and in the flatlands until Interlaken. From Thun to Interlaken you have Thunersee (Lake Thun) on your left, and occasional far off views of mountain tops. You don't go up until you get on the narrow gauge above Interlaken Ost.

You could go Zurich - Luzern - Brunig Pass - Meiringen - Interlaken Ost (have to change at Interlaken Ost, train ends there).

That route is not the default. It has to be routed that way as it is slower and longer.

It is standard SBB trains as far as Luzern, a beautiful town on the Vierwaldstaettersee (Four wooded cantons Lake, known in English as Lake Lucerne). Change trains onto the narrow gauge up and over the Brunig Pass using the rack, sometimes called by Americans a cog). Through the mountain forest with views of lakes, mountains and waterfalls, via Meiringen where Reichenbach Falls is of Sherlock Holmes fame and into Interlaken Ost with the Brienzersee (Lake Brienz in English) out the left side of the train.

I highly recommend the route via Luzern. Going directly there from Zurich airport is a good idea.