Switzerland in early May 2017

I would visit either the Zermatt area or the Berner Oberland area (where Interlaken is), but not both. Since you are a first time visitor my advice is to choose the Berner Oberland because the alps are more impressive (in my opinion) and there is more to do in the region in the event of poor weather. I think Lauterbrunnen, Wengen, or Murren are better choices than Interlaken if you choose the Berner Oberland. Unlike Interlaken these three towns are actually in the mountains.

I would skip Zurich and replace it with nearby Luzern (also known as Lucerne). Zurich is a fine city but the consensus is that Luzern is cuter and has easy access to two impressive mountain peak excursions: Pilatus and Rigi. Many people end their Switzerland trip by flying out of Zurich, so they want to stay there the night before they depart. However, Luzern has a direct rail link to the Zurich airport. Trains leave Luzern every half hour and take about 70 minutes to get to the airport, so it's easy to stay your last few nights in Luzern and make your flight with time to spare.

For 5 nights for a first timer, I would recommend 3 nights in the Berner Oberland (Lauterbrunnen, Murren, or Wengen) and then 2 nights in Luzern.

Also - how many people are in your group? A full Swiss Pass is probably overkill for a 5 night itinerary; usually a half-fare card works out best. Others here know much more about the many Swiss rail pass options.

I get it. You want to see both the Matterhorn and Jungfrau. Go for it, and good luck with the weather. Choose Luzern for your last night - it's easy and quick to access Zurich for your departure.

IMHO, that's too much moving around for such a VERY short Itinerary and therefore too much time spent in travel between locations. I'd suggest choosing either Zermatt or the Berner Oberland, as well as Lucerne (my preference would be the Berner Oberland and Lucerne).

The answer on which rail pass to buy for Switzerland is complicated and will depend to a large extent what you plan on seeing while there. You may find that a Half Fare card is the best choice, or possibly a few P-P tickets along with a regional pass such as the Berner Oberland Pass. Once you've chosen which places to visit, you'll need to sit down with a sharp pencil and analyze the cost of P-P tickets, with or without each of the Passes. Most passes only provide a discount on the mountain lifts, so you'll need to have some idea which lifts you'll be using.

You may find this helpful.....

https://www.ricksteves.com/travel-tips/transportation/trains/switzerland-rail-passes

Also note... early May is not a good time of the year to visit the Alps. Since you want to visit to see the wonderful alpine views, realize that early May is usually overcast and rainy in the mountains. This doesn't mean that you won't see the mountains, it just means that you may go several days in a row with nothing but fog and overcast skies. Also, most of the trails for hiking will be impassable. Because of this, much of the tourist infrastructure in the mountains shuts down temporarily between the end of the ski season and the begining of the hiking season (which usually doesn't get fully up and running until late June, depending on the prevailing seasonal conditions). Finally, although the exact timing varies year to year, as soon as the snowpack retreats away from the pastures, the farmers use this opportunity to fertilize the grazing land... with liquified manure sprayed through a power hose.

I'm not saying don't visit, but because you picked a marginal time of year, go with a different set of expectations. Pick one Alpine destination and stick with it. Otherwise, you may find yourself going from one overcast fog bank to another, and missing your chance to behold the mountains you paid so dearly to experience.