After lots of research, I think individual tickets outside of Switzerland, and Swiss pass flex 4 day are our best options. Please see if I am off track or missing something important. Thanks!
Mid July 2018 family Europe trip – 2 adults, 2 youth (both 21), 2nd class whenever possible
TGV from Paris to Basel ~30 euros/person + 35 seat resv. fee
Basel to Lauterbrunnen ~70 CHF, Lauterbrunnen to Murren ~6 CHF for cable car and train (staying 2 nights Chalet Fontana, cable car to Schilthorn, would like to hike down from Birg ), then somehow back to Lauterbrunnen, maybe via bicycle? To stay in Hostel 1 night
Lauterbrunnen to Brig ~ 54 CHF, get Glacier Express to St. Moritz ~115 CHF + 33-43 resv. fee, then on to Pontresina
Pontresina or St. Moritz to Munich ~70 CHF, little cheaper from DB Bahn
Munich to Fussen ~14 Euros
Fussen to Munich ~14 Euros, Munich to Venice via Nightjet 4 berth Couchette ~ 250 Euros (for all 4 tickets)
Venice to Rome ~40-90 Euros, 10 resv. fee
4 Country select Eurail – 6 day Youth $347, Adult $368 Euros (no 2nd class option for adults); 5 day Youth $318, Adult $338
Would have to buy supplement on nightjet through Austria, reservations fees for TGV from Paris, Glacier Express, NJ, & Rome to Venice, 75% of Schilthorn ticket, ticket from Interlaken to Murren and Fussen to Munich (because counted as separate day then nightjet), – these costs ~212 per person
Costs of travel inside Switzerland seem ~334 per person, including Glacier Express resv. fee
Costs of travel outside Switzerland seem ~221.50 per person
Swiss travel pass flex 4 day seems like most economical/easy to use option at Youth - 265, Adult - 310
Swiss 1/2 fare card would be more expensive for youth, little cheaper for adult (overall cost) but also have hassle of buying tickets
Berner Oberland regional pass - more expensive based on coverage area
These ticket prices are from the individual country rail sites