Swiss in July end and Aug first week

Thanks Dick...!!! We are quite worried about the weather in the mountains as we come from tropical area and not used to such a cold weather....Can any one suggest me the places not to miss in and around Zermatt.... Also we are planning to stay in Lauterbrunnen and visit mount jungfrau from there.... I would like to get suggestions on whether to stay in Gimmelwald or Lauterbrunnen

Gimmelwald is the idyllic, quiet locale popularized by our host, Rick Steves. As such, if you want to stay there 5 weeks from now, you had better secure your lodging NOW.
Lauterbrunnen is in the bottom of a deep, beautiful valley. It will be the least expensive locale, and most convenient for visiting other sites in the area. Only downside would be that it gets less sunlight because of its location, but if you are traveling every day, that might not matter.
Wengen is up on the mountain on the way to the Jungfrau. It is car free, but busier than Muerren, and way busier than Gimmelwald. It is the most convenient spot to go to the Jungfraujoch. Higher prices than Lauterbrunnen.

Zermatt? You can take the Gornergrat train up for a great view of the Matterhorn. You can also take the cableways up to the Klein Matterhorn for a close up view of the Matterhorn, as well as walk inside of a museum carved into the ice of the glacier. That warm jacket will come in handy.

We would recommend adjustable layers, no heavy coat. For instance, a lightweight fleece, windbreaker, and other underlayers. You can check the weather reports at the bottom of the lifts before going up.

Thanks Sam and Laura...!!! I had one more question, as I saw from the swiss rail map there is no direct train from Interlaken to Gimmelwald....How can I reach Gimmelwald from Zermatt should I travel via Interlaken.... Also If I have to make a day trip to mount jungfrau from Gimmelwald which route should I take...or is it better to make a day trip from Lauterbrunnen to Gimmelwald and Schilthorn...if so is there any bus from Lauterbrunnen to Stechelberg in the morning?

These are all well connected by pulbic transportation.
Zermatt to Gimmelwald: train Zermatt to Visp, connect to train to Spiez, connect to train to Interlaken Ost, connect to a train to Lauterbrunnen, then take a short bus ride to Steckleberg where you ride to Gimmelwald on a cable car. If all that sounds daunting, it really isn't because the Swiss have their transportation working like a, well like a Swiss watch. The trains and buses are all timed to connect seamlessly.
If you stay in Gimmelwald, you will takes the cable car down to Steckelberg, bus to Lauterbrunnen where you can get a train up to the Jungfraujoch. Everything runs continuously from early morning to late evening.
Edit- and the cable car to Schilthorn is right there in Gimmelwald.

Thanks a lot for all the details Sam...Just have one last question we will have two suitcases and hope it will not be a problem to take it in the cable car to Gimmelwald...We have a Swiss pass so is the cable car rides to Gimmelwald/Murren included in that? Also as Am a vegetarian(but can eat cheese and milk products) is veg food available in Gimmelwald ?

Yes, the cable car to Gimmelwald is included in the Swiss Pass.
You'll have cheese coming out your ears before you're done, Fondue (with just the bread and melted cheese kind), Raclette (cheese melted over small potatoes and onions). The Roesti you may need to specify vegetarian. And there some oriental restaurants in Muerren.
Try and see if you can cut your luggage down to one suitcase and a small back pack. You'll be glad you did.
There will be occasions with rough streets that will be hard on those wheels.
Edit- By "we", I assume there at least 2 of you. Just make sure each person can handle their own luggage in one shot, i.e. getting on and off trains. Those clockwork train connections mean you need to move when have to.

Thanks a lot Sam for all your replies...We are a couple travelling....I will try and cut down to one suitcase so that it will be easy to travel....!!!

I had one more question...Planning to visit Rhine falls in Swiss....Also want to take a boat ride to the rocks....Should I book the boat ride tickets in advance, saw that its not covered in the swiss pass....Also am planning for around 2 hours in the Rhine falls area before heading back to Zurich is that enough?