8 nights/9 Days Swiss itinerary Suggestions

I'm planning to visit Switzerland for 8 nights starting 07 September. I will commence trip from Zurich and will end it in Geneva.

I want to cover as much scenic train journeys as I can. Below is draft

Day 1 : 07 Sep: Arrive Zurich and transfer to Lucerne. Explore Mt. Titlis. Overnight at Lucerne.

Day 2: 08 Sep: Explore Mt. Pilatus. Overnight at Lucerne.

Day 3: 09 Sep. Transfer to St. Moritz.Explore St. Moritz for the day. Overnight at St. Moritz.

Day 4: 10 Sep. Glacier Express from St. Moritz to Zermatt. Overnight at Zermatt

Day 5: 11 Sep. cogwheel railway up to the Gornergrat. Then come to Interlaken. Overnight at Interlaken.

Day 6: 12 Sep. Explore Jungfraujoch . Overnight at Interlaken.

Day 7: 13 Sep. Panoramic-Express (Golden Pass) Train from Interlaken to Geneva (via Zweisimmen). Overnight at Geneva

Day 8: 14 Sep: Explore Geneva. Overnight at Geneva

Day 9: Head Back

I am traveling with my wife.

Please could you comment on above plan? Also should I buy 8 days Swiss pass (if that's more economical).

Thanks,
Sail