one week in switzerland in July with 2 elementary school kids

Slightly better, I think is:
Day 1: Train from airport to Lucerne (1 1/4 hour). Sightseeing Lucerne; Night in Lucerne
Day 2: Sightseeing Lucerne; Night in Lucerne
It is just a little longer to get to Chur from Lucerne, but still doable. 8:35 departure, change trains in Thalwil, arrive Chur at 10:43 with plenty of time to get the first Glacier Express of the day shortly after 11:00. Lucerne much better location than Zurich with lots to do and see.
Day 5: Sightseeing Jungfraujock(sic); Night in Bern
This will be totally weather dependent. Even with a Swiss Travel Pass, a trip to the Jungfraujoch will run close to 75 CHF. If the weather is not clear, don't waste your money. Have some warm clothes.
Day 6: Bern Sightseeing; Night in Lausanne
Day 7: Sightseeing Lausanne; Night in Lausanne
Again, more to see and do in Lausanne. It is only a 45 minute train ride from Lausanne to Geneva Airport.

Lodging will be very limited this summer, due to pent-up demand, so decide and book asap. Finding places that fit your needs and budget may determine your itinerary. Good luck!

Too much moving around, especially with kids. You’d be exhausted and spend over half of your time on trains lugging around your luggage. A week is not enough time to see all these things and you need atleast 1 full day without moving in each place to actually see anything. Here are a couple examples that might work depending on what you want to prioritize.

Day 1 - Arrive in Zurich, immediately train to Luzern (stay 2 nights)
Day 2 - Luzern
Day 3 - Luzern to Interlaken (stay 3 nights)
Day 4 - Interlaken / Wengen / Jungfraujoch
Day 5 - Interlaken / TONS of great options for kids up in the mountains or if you really want, a day trip to Bern but I think they'd enjoy some of the mountain activities more.
Day 6 - Interlaken to Montreaux
Day 7 - Montreux
Day 8 - Assuming based on your itinerary that you’re departing from Geneva? So train from Montreaux to Geneva in the morning to depart.

Day 1 - Zurich
Day 2 - Glacier Express to Zermatt
Day 3 - Zermatt
Day 4 - Zermatt to Interlaken
Day 5 - Interlaken / Wengen / Jungfraujoch
Day 6 - Interlaken / TONS of great options for kids up in the mountains or if you really want, a day trip to Bern but I think they'd enjoy some of the mountain activities more.
Day 7 - Interlaken to Montreaux
Day 8 - Assuming based on your itinerary that you’re departing from Geneva? So train from Montreaux to Geneva in the morning to depart

Thanks. I think we will drop the glacier express and Zermatt to keep the trip little chill.

From kristyn's first itinerary:

Day 3 - Luzern to Interlaken (stay 3 nights)

The train from Luzern to Interlaken is quite scenic

Day 6 - Interlaken to Montreaux

The Golden Pass Express train from Interlaken to Montreux is also quite scenic

So I think you have scenic train rides covered with this itinerary.