Swiss Rail Pass or regular tickets

If that is just what you are doing (Luzern to Wengen and Wengen to Basel), then a pass makes no sense, just buy the individual tickets at the station. They will cost CHF 47.40 and CHF 75.40 respectively. No discount for advance purchase. Tickets are valid on any train that day, you can decide which train when you get to the station.

Basel to Paris is a French train, here you will get a discount by booking in advance. and tickets are specific to one train, with the train ID and your seat numbers on it.

Are you staying overnight in Basel or continuing the same day to Paris. If Wengen to Paris is on one day, you may get a cheaper price by making that one purchase.

If you have more than 240 CHF of tickets, then the 30- day Half Fare Card at 120 CHF pp will save you money. The other journeys you planned are pretty expensive. To go to the Jungfraujoch from Wengen, the Swiss Travel Pass only gives a 25% discount, but fully covers the Schilthornbahn lift. The Half Fare Card gives 50% off for everything.

If you want a real answer, you'll have to add the costs of every trip, note how each is covered by different passes. Most prices can be got from www.sbb.ch/en. Remember the first price you see says " 1 half fare card plus ticket", meaning that the price assumes you already have a Half Fare Card, so you have to double it if you don't have one. Prices for the Maennlichen lifts at https://www.maennlichen.ch/en/tschuggen-skilift.html.

So for the tickets to Wengen from Lucerne and the Tickets to Basel (we are not staying the night), I should buy those now, not get a pass and then get a pass for the ones while we are there going to all the sights we are going to do? Which pass should we get (look at) with the things I was looking at?

You do not need to buy those tickets now, since the trains are all unreserved and the price is fixed (generally). Again, your decision on getting a Swiss Travel Pass, of a 30-day Half Fare Card, or a Berner Oberland Pass is up to you. Do the math, its not rocket science.

You do not need to buy any Swiss rail tickets in advance, but you MUST buy French TGV tickets in advance.
Do not buy Luzern to Wengen in advance.
Try to buy Wengen to Paris as one purchase in advance, as this may be cheaper than Wengen to Basel + Basel to Paris. If not, just buy Basel to Paris in advance and Wengen to Basel on the day.

At a minimum, I would buy the Half-Fare Card, which is sure to save money over full fare once you add in the mountain routes. If you choose a Swiss Travel Pass, it would probably be for 8 consecutive days, even though you'll only use it for 6 days. See more costs to compare at https://www.ricksteves.com/travel-tips/transportation/trains/switzerland-rail-passes and through the JungfauBahn link on that page.

To help you compare the value of different passes versus individual tickets, here are some links:

Berner Oberland Regional Pass: It covers from Luzern on into all that stuff you want to do around Wengen, and also as far as Bern on your way to Basel (click on the "synoptic map" link to see what it covers fully and partially)
https://www.regionalpass-berneroberland.ch/en/pass-and-infos/the-ticket/

Swiss Half Fare Card:
https://www.sbb.ch/en/leisure-holidays/travel-in-switzerland/international-guests/swiss-halffare-card.html

Swiss Travel Pass:
https://www.sbb.ch/en/leisure-holidays/travel-in-switzerland/international-guests/swiss-travel-pass.html

Individual Tickets: (Default price shown is half-price, with assumption that you have a Half Fare Card)
https://www.sbb.ch/en/home.html

We went with the half fare care for the time that we were there. We had a wonderful time and loved Switzerland! We had such a wonderful time and saw just about everything on our list. We decided not to do Schilthorn but had a. nice relaxin day in Wengen instead. We were able to see more then I thought and could have added a lot more but the down time was actually nice!!

Thanks for the update!

Just to confuse you more, from the Berner Oberland you can also get to Paris via Lausanne or Geneva if the Basel>Paris trains are sold out at the lower prices.