I DAY in Zurich is More then sufficient.
In Zurich you can visit CENTRAL by tram . from CENTRAL have a walk to beautiful churches, Limmat river, view point ( full view of city) and at last walk down to Bahnhofstrasse ( a beautiful road around which you can see the stores,people, fountain and beautiful cars)
lucern is best place to stay as lucern has best connectivity to all the location, else you an stay in Engelberg if you want feel your stay more peaceful and close to nature. For Mt titlis you have to come to Engelberg , free bus shuttle available to titlis base station. if you have swiss travell pass then Titlis tour is free for you.
pilatus is very near to Lucern. the Pilatus tour will cost 36 chf if you have swiss travell pass (50% discount on swiss travell pass) .Take a mounain coaster ride at pilatus at 35 chf per pax.
Grindelwald, Trummelbach falls, Lauterbrunnen valley, Murren all falls in same route to Schilthron. you take a train from Lauterbrunnen and then a small ride from bus.it will take a complete day if you want to cover all from luzern as it takes 5 hour to reach from train.
if you are staying at various hotels , you have to pay city tax 2 chf per day per person.Airfare is high during peak season ( july to oct).
itinerary for 8 day
1 day in zurich
2 day titis tour
3 day lucern city tour ( glacior mt park, dying lion, lake , church, old city ,clock tower, dinner at cruse )
4 day to Bern city tour. (aare river, city tour, park, parliament etc ). Thun is near to Bern, The castles of Thun, Oberhofen and Spiez on Lake Thun invite families to immerse themselves in the world of the middle ages.
5 day to schilthron ( it will cover , Lauterbrunnen, murren, Grindelwald ,Trummelbach falls)
6 day to beautiful chillon castel in montreux. it will take full day if you are staying in Luzern. 8 hour round trip.
7 day mt pilatus at luzern.
8 day to lake geneva