After 4 nights in Zermatt we visited Lucerne. Stayed there for 4 nights and I feel that Lucerne is a good base for a day trip to Bern, Basel.
We didn't go to Mt.Titlis this time because we had enough of Swiss alps experience in Zermatt.

Train to Lucerne from Zermatt is not really ideal because we need to change train at 2 different stops and the connecting time is very little. For those who travel with family/ a lot luggages it's a bit hard but still doable.
My suggestion is to purchase the flexible / day trip train where you can use any train at any time. With discounted fix ticket, if you miss the connecting train then you have to purchase a brand new ticket.

Lucerne
For those who stay in a hotel, do not forget to ask the hotel for the tourist pass where you can use bus for free during your stay.
I stayed at Radisson Blu Hotel and it's about 5 minutes walk from the main train station.
Hotel itself is good, clean and modern rooms with connecting door if you book 2 rooms for the family.

Things to do in Lucerne:
Stroll around Lucerne old town which is very nice with a lot of good restaurants / Cafe next to the chapel bridge.