Need suggestions for our switzerland trip

Hi kavitha, and welcome! That's quite a full travel schedule, but if you don't mind long traveling times (for example on day 5 and 6) that's fine of course. Did you check the timetable to find out about the exact duration of all trips? Personally, I would prefer to spend the extra day in the Interlaken region. It's stunning and offers wonderful scenery, two beautiful lakes and several viewing points. I would even consider to skip the day trip to Zermatt to spend one more day there. This will also reduce traveling times and create a bit more space in your itinerary. But if you want to see as many different regions of the country as possible, your itinerary is great.

With an 8 day Swiss Saver Pass you'll be flexible indeed (buying regular tickets for Zurich-Lucerne on day 1). This is definitely the right choice for your plans. You may adapt your plans according to the weather. For example: if weather is fine, you may prefer a boat ride over lake Thun or lake Brienz, or an easy hike in one of the beautiful valleys, over a cheese and chocolate factory visit. This is no problem with your Swiss Pass. Current purchase options are listed at the Swiss Pass page. This offer may be interesting to you.

As for clothing: you should be prepared for all kinds of weather. If you're lucky, you'll get to enjoy beautiful summer weather. But it may be cold and rainy as well. Anyhow, it will be pretty cold up at Mt. Tilis, the Jungfraujoch and other viewing points you may visit. So solid shoes and warm jackets are comfortable for those trips.