Quick visit to Switzerland in October

If it's early October, weather tends to be pretty good. Moderate temperatures, low humidity and on the drier side (but this doesn't rule out rain, however). Later in the month, though, the atmosphere becomes increasingly damp, and those picture-perfect views you dreamed of start hiding behind a veil of grey fog.

If heading to the Alps, base yourself in one location and stay there. Even at good times of the year, the micro-climates of the mountains can wreck havoc on your travel dreams unless you play the odds. And the odds favor not dashing about from one location to the next. That way when good weather strikes, you're there to enjoy it

Sounds like a daytrip or an overnight in Interlaken/Lauterbrunnen would work for you, taking cable cars/trams up to either the Jungfrau or Schilthorn. No hiking needed.

Lucerne would be a good place to hang out near a lake with the mountains in the background.

Forget about a car, use train, tram and bus.

Or, train/fly to Zurich and after some time in Lucerne, you could take the Golden Pass to Interlaken as above, then continue on to Montreux/Lausaunne and take TGV back to Paris.

Do you think, one day to Provence will make sense instead of Montreux/Lausaunne and then leave towards Interlaken in evening or next day morning ? Just to see different kind of scenery.

I noticed that Provence will be completely out of way and should not make any sense.
Initially I planned to stay at same place for all three nights, as all suggest. I was searching trains from Paris to Murren for my first night stay, as suggested by you.
My flight at Paris will land at 11:20 AM. After custom clearance, I will need to go to Gare de Lyon and take train for Basel. If I assume that, I will not be able to catch train till 13:00. I can see one train starts at 13:55 from Paris-Est and reach Murren at 22:05 after changing trains/bus and cable car. And obviously I will miss few trains also, being new to this system. Will it be convenient to reach there so late or should I stay somewhere else ?
May be I can stay just for first night, before any scenic place will start for next day.
What place should I keep to see on my last day before leaving to Paris ?

My flight at Paris will land at 11:20 AM. After custom clearance, I will need to go to Gare de Lyon and take train for Basel. If I assume that, I will not be able to catch train till 13:00. I can see one train starts at 13:55

The easiest way to get to Gare de Lyon is by taxi. The second easiest is with Les Cars Air France - a comfortable bus that goes non-stop to Gare de Lyon from CDG (is that where you're landing?) The bus takes about an hour. There are buses every half hour. The third way is by RER which could be fastest, but you have to change trains. What time you get to the Gare de Lyon depends on:

• what time your flight lands - it can be delayed for numerous reasons
• how long you wait in line at passport control - 2 minutes? 45 minutes?
• whether you have to wait for baggage
• then allow 10 minutes to walk to the bus stop, up to 30 minutes wait for the bus, possible traffic delays, 10 minutes from the bus stop to walk to the station and find your train. Or walk to RER (long or short depending on your terminal), then wait for the train, transfer to another RER (add waiting time) at Gare du Nord.

I will be landing at CDG at 11:30 AM. You are right, custom clearance and other factors (you mentioned) can delay my time. I was doing some more readings about feasibility and economical travel and got one more option.

There is a flight 16:00 - 17:10 (Air France) from CDG to Geneva. If my flight reaches at 11:30 AM, based on my other international flight experience, it should easily take 2+ hours to complete all formalities and checks. Then pre-checks of another flight (Paris to Geneva), which should starts at 15:00. So, if at all, I need to take flight from same airport, 16:00 is only good time.
If I have to think from money and time factor for all travels (by train or flight or mix-match), I can see two options -

BY FLIGHT -

Day-1: Reach Paris at 11:30 AM. Flight to Geneva at 16:00. Take train towards Stechelberg/Murren/Lauterbrunnen ($55 per person)

Day-2: Jungfrau Area

Day-3: Lucern Area

Day-4: Lake Thun or Jungfrau train or Lake or Wengen trails. Then leave to Paris from Basel Airport ($55 per person)

Day-5: Full day in Paris and nearby, for main attractions.

Day-6: Leave hotel in morning. Fly out from CDG at 10:30 AM

BY TRAIN -

Day-1: Reach Paris at 11:30 AM. Leave further to Stechelberg/Murren/Lauterbrunnen via Basel

Day-2: Jungfrau Area

Day-3: Lucern Area

Day-4: Golden Pass train, Lake Geneva, Chateau de Chillon and then to Paris.

Day-5: Full day in Paris and nearby, for main attractions.

Day-6: Leave hotel in morning. Fly out from CDG at 10:30 AM

In flight option, I will have to pay $220 for Paris-Geneva & Basel-Paris. In train option, I will be buying some pass. I am still trying to understand and learning rail system. Which option, do you think, is better and economical according to my itinerary ? Or you want me to change something else ?

If you go with the train option, I think taking the TGV to Geneva from Paris (and back) would cut a good bit of time off the Basel route (but prob. more expensive). Then you have a lovely train ride from Geneva to the Berner Oberland/Jungfrau region.