Please help us with a Swiss Pass

You really do not have enough travel to justify a pass or half fare card.
You can check prices at www.sbb.ch/en. Keep in mind that the first price shown as "price from CHF XX.XX" assumes you already have a half fare card. You can click on the "Fare/Buy" button and mark "no reduction" in the drop-down menu to get the real price, normally twice the "from" price.
The Allmendhubelbahn is 13 CHF round trip. The Lausanne-Montreux-Lausanne day trip can be done with local 7-zone day pass for about 25 CHF. Depending on your hotel, it may include free local transportation.
I do not see you having more than 240 CHF of tickets, which is the break-even point for the half fare card.

If your trip fit within 4 consecutive days, I could see buying a pass for 251 CHF/ $263 to include coverage of small items like museums. When you need to spread those days out, the pass price goes up (286 CHF/$299 for 4 flexi) and you have a day with no coverage.

Thank you for the information. Sam, I didn't realize that the SBB already assumes we have a half fare card. Good to know. When I times the price on SBB by 2 it turns out to be $205 without the Montreaux day trip. Our hotel in Lausanne does give us a transport card, but I don't think it is valid all the way to Montreaux. Laura, we will mainly need to use the trains on our first and last days in Switzerland which pushes us over 4 consecutive days.

Your Lausanne Tourism local transport card will get you 3 zones of the 7 zone distance to Montreux, so if you get a 5 zone day ticket, it will knock down that 25 CHF day ticket down to 9 CHF.
http://www.t-l.ch/images/pdf/plan/mobilis-plan-general.pdf
Edit- I took the 5 zone price by checking the price from Epesses to Montreux, but a 4 zone ticket will work as well when I think about it for a bit less.

Thanks, Sam. Every little bit helps in Switzerland!