Rail Pass - Which one?

How are you getting to Lugano and leaving Luxembourg? Fly into Milan and home from Luxembourg airport?

Flying into Milan. Taking a train to Lugano same day as arrival. From Luxembourg City we will train to Brussels and then to Delft and finally Amsterdam. Flying out of Amsterdam.

Two basic choices, which I think you have identified.

1. Get a Eurail 7-day Global Pass for 2 traveling together at all times for $1168.
   Pluses: It is 1st class. With a few exceptions, just hop on the train and show your pass to the conductor when he comes around.
   Minuses: The section between Interlaken Ost to Wengen is not covered, but the pass does give you a 25% discount. You will not be using a pass-day for lifts, so other than your arrival and departure days, you will pay full fare. Thinking of the Jungfraujoch? It is expensive!

2. Buy Swiss Half Fare Cards and buy tickets as you go. I figure $900 at today's exchange rate for tickets and Half Fare cards.
   Pluses: Less cost. Also, your Half Fare cards cover everything including the lifts in Wengen or anywhere else in Switzerland including boats and city buses.
   Minuses: 2nd class. Each ticket has to be bought before every journey.

A couple of added comments. I did not figure you using any TGV or Thalys trains. With a Eurail Pass, there are very high reservation fees, and the one useful TGV, from Mulhouse direct to Luxembourg could have restrictions on the number of pass holders allowed on the train. There is only one of these every day and it is coming from the Mediterrenean coast. The Thalys train for the Brussels to Delft has high reservation fees, so I figured using an IC train which adds about 50 minutes to the travel time.

There is a bus direct from Milan airport to Lugano. That could save going into Milan and coming back to Lugano. The train to Milan is not covered by the Eurail Pass, and you may have to pay a small reservation fee for the train to Lugano.
Delft to Amsterdam is only about a 15 EUR per person ride, so no use using a pass day unless you happen to have an unused day left on the pass.

I would not usually suggest two overlapping pass products. Your suggestion of a 15-day Consecutive Global pass plus the Swiss Half Fare Card adds up to about $750 per person, plus 50% of the ticket prices in the Lauterbrunnen Valley, and on the top half of Mt. Pilatus, and on some lake boats.

Benelux is a package deal. If considering a Eurail pass, the Select Pass for travel in 4 "countries" is a bit cheaper than the Global Pass and could cover Italy, Switzerland, Benelux, and France. Or a Select Pass for just France-Benelux is available in 2nd class, about $270 per person for 4 days of travel, but you'd want to avoid the reserved Thalys train between Brussels and Rotterdam. I estimate that buying tickets as you go to your stated destinations will cost a bit less in 2nd class (for the two-country pass; that's the only one I added up).

I think I'd prefer the Swiss Travel Pass for 8 consecutive days, $418 per person, which I think will cover your whole Swiss plan from the day you depart Lugano by train through your train from Lausanne to Basel (connection point), with just a couple of mountain lifts costing extra. Then buy tickets locally for the trains in other countries.

See What do rail passes cover in Switzerland? for a list of key differences between the STP and multi-country Eurail passes.

For the Swiss section, The Half Fare card saves the most money. Just on your stated itinerary of 4 legs, you have 260 CHF of full fare train tickets, with a routing through Zwesimmen on the leg between Wengen and Lausanne. Thought you might want to travel the scenic Golden Pass route.

Since this is more than 240 CHF, the 120 CHF Half Fare card will save a small amount, but also give you half fare for any mountain lifts and city transportation while in Switzerland.

The 8-day Swiss Travel Pass at 398 CHF is about 150 CHF more expensive. It does include the Schilthorn all the way to the top, but only a 25% discount from Wengen to the Jungfraujoch. And it does give free city transport and most boat trips, and you don't have to buy individual tickets, except mountain lifts where you still have to pay something.

The 2 country Eurail pass does not save anything except the convenience of having to buy tickets. You have 155 EUR per person worth of tickets, $190 at current exchange, so $270 per person for a rail pass means you are paying $80 per person for that convenience.

Thank you, that is what I was looking for!