Switzerland travel - Pass?

Well, looks extraordinarily well planned, maybe too well planned. I don't see how you'll get it all in, but you can edit your plan as you go.
How old is your son? If under 16, you can get a Swiss Family Card (no charge) and he'll travel free as long as you have some sort of Pass or Half Fare Card. If 16 or above, he travels as an adult.
The one month Half Fare Card for 120 chf per person will usually save the most. Half fare on local transit, buses, trains including the Jungfraujoch. The 4 day Saver Pass is 245 chf per adult, but only gives a 25% discount on the Jungfraujochbahn above Wengen.

Thanks Sam.

For starters though, it's me and Mom and Dad.. not wife and kid :D. Both my parents are above 60 though, so do let me know if there are any discounts available.

You mentioned a 1 Month card, but I'm only there for 5 days or so - does that still work out to be the cheapest option? The point really is, is there anything that I can use to make unlimited rides using the train/bus/tram system in Switzerland - that covers all the places that I hope to cover?

The one month Half Fare Card refers to the maximum length of validity. It works for just a weekend, if that is all the longer you are there. The key is that you need to have over 240 chf worth of train tickets for one person to make it pay. On your itinerary, the Jungfraujoch excursion is the big ticket item. It is 176.20 chf per person for a round trip from Lauterbrunnen. Combined with Zurich to Lauterbrunnen and Lauterbrunnen to Geneva, that will exceed 240 chf. Note that if you do not do the Jungfraujoch because of bad weather, you will have "left some money on the table" as we say.
Looking at your structured itinerary, you should make this journey at the first opportunity that weather permits. Mountain weather can be very changeable, and there is not much point in making such an expensive trip if the mountain top is covered in clouds.
The card will also work on the lake boats, local trams and buses in Zurich, Lauterbrunnen, and Geneva.
http://www.sbb.ch/en/leisure-holidays/holidays--short-breaks-in-switzerland/swisstravelsystem/swiss-halffare-card.html

Excellent. That makes a lot of sense - thank you very much Sam. I will keep your tips about doing Jungfrau as soon as there is a clear day.

Just one additional question - I noticed a lot of cable car and gondola travel in Switzerland - that I guess will have to be separately paid for when needed? - or does the pass cover that as well?

It's been an insane insane amount of planning really - largely because my elderly parents are with me and they'll have some physical limitations. I hope it all goes well. Thank You again.

Click on the "Details" section of the link I provided. At the bottom you'll see another link "Map of validity pdf". That will give a rail map of Switzerland that shows all the cable cars that accept the Half Fare Card. And remember, it is not a pass but a card that allows you to purchase tickets at half fare, either 1st or 2nd class. You can buy the cards at Zurich station when you arrive.

Ah.. so I buy the card and THEN buy individual tickets?

For eg. The card is 120 CHF apparently. Say I buy it. Then say the Jungfrau trip is 200 Euro (for simplicity). Since I have a half fare card, I'll be buying it for 100 Euro. Meaning spending a total of 120 + 100 = 220 Euro. If I didn't have the card, I'd pay 200 Euro.

The more the number of journeys, the more useful this is, correct?