<<"As I am with parents I would like a relaxed holiday rather than hopping on ad off continuously. Can anyone suggest any 3 day internery?">>
That is not a very relaxed schedule, although you can do it.
One option that you might consider - Geneva -> Luzern (include a mountain excursion to Pilatus - it is impressive and close to Luzern) and explore Luzern.
The forum moderators sometimes recommend the Golden Pass route from Geneva to Luzern, via Lausanne, Montreux, Zweisimmen, Spiez, Brienz, the Brunnig Pass, to Luzern. It is very scenic and a wonderful ride. 5+1/2 hours.
If you are in hurry, you might look at Geneva- Bern - Luzern as an alternate routing. Less scenic. Faster.
2hrs 45 minutes to 3 hrs 10 minutes.
Here is a link to the Swiss Rail web site.
Use the "via" box to alter the route. Use Zweisimmen for the Golden Pass, use Bern for the fast route. The computer automatically picks the fastest one if you leave the "via" box blank.
Opinions vary, but I find Luzern to be a better tourist destination than Geneva. Probably just my perspective, but the forum moderators routinely recommend Luzern and the Jungfrau area as the best places for a first trip to Switzerland.
Forgive my spelling - Luzern is the German spelling, and Luzern is in the German -speaking part of Switzerland. My habits control my typing fingers, frequently.
Your idea of Interlaken as the destination after Geneva as the second day is also very good. It would allow a shorter rail trip on the Golden Pass route, could include the Jungfrau if the weather is good, and still be close to Bern for your departure.
Either Luzern or Interlaken have good connections to Bern. Interlaken has more 1 hour or less connections, Luzern has some 1 hour connections and others at 1 hour and 1/2.
Depending on what time you leave from Bern, you could stay in Luzern, Interlaken or Bern.
Either of the choices will give you a great trip.