Train travel

I would only get the one Swiss Travel Pass, rather than doubling up. If fully covers Muerren/Gimmelwald/Schilthorn and on the other side of the valley, fully covers as far as Wengen or Grindelwald, and then offers 25% off above those points. And you're covered toward Italy as far as Domodossola, Chiaso, or Tirano.

And if you’re a train newbie and don’t really understand how the whole public transport thing works then the STP is definitely for you. It’s rather fool-proof and requires no knowledge on your part other than what train to step onto. Just know that before you travel to the Jungfrau you need to go to the ticket counter, tell them where you want to go and that you have the STP. They will sell you the correct ticket.

My wife and I are traveling from Aug 17-24th and we begin by arriving in Zurich. We will go immediately to Lucerne for one day, and then on to Wengen. We'll be in the Bernese Oberland region for 2 1/2 days, and then we head to Como, Italy and fly home from Milan.
So that would be 3 point to point train trips over 4 days,

I count 4 train trips, only 2 and part of a third are in Switzerland and covered by the Swiss Pass

1) Zürich Flughafen (=airport, I assume you are arriving by air) to Luzern: 1 hour 10 minutes, CHF 30
2) Luzern to Wengen: 2h45, CHF 47.40,
3) Wengen to Como S. Giovanni (= Como town, or are you staying somewhere else on Lake Como?). Approx 6 hours.
Swiss pass only valid as far as the border station (Domodossola). Cost to Domodossola CHF 70.40
4) Como to Milan Malpensa airport (is that the correct airport?).

All prices from Swiss Railways website: https://www.sbb.ch/en/

For 2½ train trips In Switzerland: 30 + 47.40 + 70 = CHF 147.40
Swiss Travel Pass Flex 3 days in 1 month = CHF 267
Swiss Travel Pass Flex for 4 days in 1 month = CHF 323.00
Not enough to justify a Swiss Pass, unless you are doing a lot of day trips.
Plus you need to buy tickets for the Italian parts.

Chris, [on my original post of 7/12/2019,] I outlined my December trip, and I thought a 4-day Swiss Travel Pass was under $300. I do want to take advantage of the museums on the pass, especially in Basel.
Did I make a mistake? I'm not finding the cost above $300.
This is why we need your local info so badly.
Thx so much.

Pat, The Swiss Pass prices are on the SBB website here: https://www.sbb.ch/en/leisure-holidays/travel-in-switzerland/international-guests/swiss-travel-pass.html

The OP said "3 point to point train trips over 4 days, and in that case I think the 4 day Swiss Travel Pass would be beneficial.", So I quoted for a 4-day pass. If he takes a flexi pass he only needs the 3-day version.

Swiss Travel Pass Flex 3 days in 1 month CHF 267
Swiss Travel Pass Flex 4 days in 1 month CHF 323

Or he could buy a 4-day consecutive pass at CHF 281 and use the extra day for an excursion. My bad, I've corrected my previous post

Swiss Travel Pass 3 days CHF 232
Swiss Travel Pass 4 days CHF 281

I'm quoting prices in CHF (Swiss Franks) which is what the prices are fixed in. If you are getting prices in $ (USD), that price will vary according to the exchange rate and resellers markup.

"We'll want to go up to Jungfraujoch and Shilthorn, to Murren and Gimmelwald, and whatever other means of transportation we will need."

Note that Chris's figures don't account for these stated mountain trips, nor anything in and around Luzern. Those costs will add up.

Chris, thanks, I now see the price discrepancy is between CONSECUTIVE day Passes and FLEXIBLE Day Passes.

So I've been doing more research, and I think I've figured out the best option for us, but I could use confirmation. It looks like it's the 4 day Swiss Travel Pass, but the most important question I need to know is - does a day count as 12:00 am to 11:59 pm (or 23:59), or does it begin with the first time it is used?

If it is 24 hour midnight to midnight, then beginning on Aug 17 with the first leg from Zurich to Lucerne, we would have to purchase a separate point to point ticket, and then on the 18th begin the 4 day period. This will take us through the last leg on Aug 21, which I think will be from Interlaken to Lugano (keeping that part in Switzerland and then taking a regional train to Como, separate cost). I've calculated a cost of 278 CHF (for 2 ppl).

But then because the cost to Shilthorn is included in the Swiss Travel Pass, and that looks to be 105 CHF each, that would bring the total to 488 CHF and the 4-day travel pass would be 562 CHF. Once all of the trains and cable cars are added in, which are included in the pass, and the discount to go up to Jungfrau, it makes total sense to get the 4 day pass. Even if it's just a small saving, or close to a break-even point, the sheer convenience that the pass offers is a big factor as well.

If the pass begins with the first use, then I believe we wouldn't need the separate point to point ticket. Any thoughts or comments?

If you buy a Swiss Travel Pass the days run midnight to midnight (00:00 to 23:59).

Photo of a 4-day flexi pass here: https://i0.wp.com/quickwhittravel.com/wp-content/uploads/2018/01/img_3664.jpg
You fill in the dates yourself, there is no place for putting the time. That incidently is why you can't get a "self-print" version of the flexi pass, you could just re-print it and get another 4 days!
The consecutive day pass has the dates pre-printed, you specify them when you buy, and you can get a self-print version.