Hi all,
we are planning to take train from Geneva to Luzern with some luggages...What is the best route to take? Any places to visit on the way? with 3 nights stay in Luzern...Most important things to cover around Luzern? Appreciate the feedback All. Thanks in advance.

There are many, many places to visit in between, and what is "most important" is entirely subjective. I would suggest that you consult a decent guidebook or two or read some trip reports. Here's mine; you might find post # 28 of particular use.
https://www.fodors.com/community/eur...-983126/page2/

Also, note that Swiss rail has a luggage forwarding option. Most transfers are in one day, pick up the next, but there are a few same-day options if the timing works. Consult the sbb website for full details.