Lets count:
Paris-Laussane: full fare for the direct TGV is 80 euro, but in case you purchase ticket in advance you can get it much cheaper. As an example, at the moment there is a promo for Paris-Geneva route starting only from 20 euro, so...
Since domestic one way tickets in Switzerland are valid only for 1 day, then you will need two separate tickets for Golden Pass line: Lausanne-Interlaken (full fare 48 CHF) and Interlaken-Lucerne (full fare 30 CHF).
Lucerne-Berlin can be easily bought online from DB website from 39 euro - just do it some time in advance.
For Italy pass is not a solution definitely, since it is "cheapest" part of your itinerary. Venice-Florence by InterCity train costs only 22.5 euro (regular fare) + you purchase 15/30 days in advance you= get 15% or 30% discount. Same story with Florence-Rome: regular IC fare is 28 euro,
EuroStar - 44 euro + potential 15%/30% discount. And if you really want you can save even more by traveling on regional trains.
So, as you can see, it is not a problem to do a trip for <200 euro per person in total. All you need - purchase couple tickets in advance.
In Interlaken - Go to the top of Jungfrau. In Luzern - Go for the Mt.Pilatus Golden Round Trip
In both cases Swiss Pass won't win you a lot on discounts. Cheapest 3 day Saver Flexi pass for US citizens costs 217 USD (230 CHF), while point-to-point Lausanne-Interlaken (full fare 48 CHF) and Interlaken-Lucerne (full fare 30 CHF) + 180 CHF for Jungfrau rail (Swiss pass gives 50% discount) + for Mt.Pilatus 90 CHF (Swiss pass gives 50% discount).
As result, if we aren't wrong with math here - Swiss Pass (+50% for Jungfrau rail and Golden Round trip Mt.Pilatus)= app. 365 CHF per person, while point-to-point tickets + full fare Jungfrau rail and Golden Round trip Mt.Pilatus= app. 350 CHF
If you go with 4 day Saver or Saver Flexi pass, then the difference is even bigger