H Hetal -
Continuing my comments -
<<"Day 7 - Long day. Little time to appreciate the places that you visit.
I agree. Can skip Zermatt and go straight to St.Moritz and enjoy the nature there. Suggestions from other members please. Also, should we do zermatt instead of gstaad on day 6 ?">>
I'm not sure what you mean here. Zermatt is not close to Gstaad or les Diablerets.
Days 6 and 7 -
Either Zermatt or St. Moritz have beautiful mountain scenery. Zermatt has spectacular mountains.
St. Moritz has more variety , because of the chain of lakes extending to the Italian border.
Checking the timetable, I see that St. Moritz takes about twice as long (5 or 6 hours to reach from Interlaken in comparison to Zermatt. ( Although there is a special route to Zermatt from Interlaken via Kandersteg that adds about an hour and has wonderful scenery.)
<<"Any specific reason to skip the rhine falls? flight is at 11.20 so staying at zurich gives peace of mind. If we leave st. moritz at around 8 and reach zurich, rhinefalls would not be possible? we have the full day with us. At most, zurich sightseeing can be skipped">>
It wil take you 3 or 3 1/2 hours to get from St. Moritz to Zürich.
That would certainly allow time to visit the Rhinefalls. My too brief comment was based on the very personal judgement that the Rhine Falls, though powerful and impressive, are not terribly high. There are many dramatic water falls around the world. On the other hand, there is only one Luzern or one St. Moritz, and they are quite distinctly Swiss.
Everyone has their own preferences, and I and my wife have visited the Rhine Falls once and have never gone back.
We have spent days in St. Moritz and weeks in and near Luzern and the lake. I think that either one deserves as much time as you can find to spend at them.
I've attached a few pictures showing the environment of Luzern and the surroundings. There are plenty of pictures of the town itself all over the internet, and here:
This link, although focused on a hike at the southern end of Lake Lucern, also has quite a few pictures of the lake:
Zürich is a nice city. My favorite...but that is for reasons of culture and various places that are not really scenic tourist attractions. Some time in the old town is nice. I like to walk the old town on both sides of the river.
The museums are quite nice, especially the Rietberg.
The Alps are distant.