>> I am planning to do Mt Titlis, Rhine falls, Bern, Lucerne and scenic train ride if time permit.
I will be staying in Zurich for all 4 nights. Mountain attractions will be good if nearby.
If you don't mind a long day on trains, you could include the Glacier Express sector between Andermatt and Chur, which travels over the magnificent Oberalppass.
To get this route to come up in the timetable, the trip would be "From Zürich" "To Zürich" "via Flüelen" "via Andermatt" and "via Chur". It would take all day, a bit over 7 hours.
Scenic highlights of this route are:
> The Zugersee (Lake Zug): The train travels high along a hillside on the eastern side of the Zugersee, and you have scenic views down to to the lake, lakeside villages, and the mountains (including the Rigi) on the other side of the lake. Sit on the right.
> The Vierwaldstättersee (Lake Lucerne): Lovely views of the lower end of the lake and towering mountains on the other side. Sit on the right.
> Wassen: The little white church of Wassen is passed three times, as the train zig-zags to and fro to climb the mountain.
> Göschenen to Andermatt: A steep climb out of Göschenen and past the rugged Schöllenenschlucht (Schöllenen Gorge) and Teufelsbrücke (Devil's Bridge). Sit on the left, ideally facing backwards, to get the best view of the gorge.
> Andermatt to Chur: Glacier Express over the Oberalppass. Magnificent mountain scenery. Reservations are compulsory for this sector.
> Chur to Zürich. Not as striking as the rest of the trip, but there are some lake views as you travel along the Walensee (Lake Walen, with the almost vertical Churfirsten mountain range on the other side of the lake), and the Zürichsee (Lake Zürich). Sit on the right.
I have attached a map of the route, and a possible itinerary showing connections: the relevant one leaves Zürich at 10:09 and takes 7 hours 14 mins.
Such a long day on trains isn't for everyone, but the scenery on this route does keep you looking out of the window! If not having lunch on the Glacier Express, it would be a good idea to bring lunch with you.