I think you are an Indian. Even, I had a visit to Switzerland recently. Zurich, Luzern, Geneva, Bern, etc. are some places to visit. Six days is a pretty good time. You can exclude Zurich, Luzern, etc. from your tour planning as they are just normal cities. You should visit Bern as it very different from these cities. Titlis, Zungfraojoch and pilatus are must to visit. Travel by train, as the scenery outside the window is breathtaking. Stay at Interlaken and Engelberg to visit is Titlis, Zungfraojoch and pilatus. Hope that helps..!! :)
My personal experience..