There is a mandatory seat reservation for long distance trains (FB and FE) for pass holders. 4046 is reservation-free.

There's a mandatory reservation for both trains (did you mean EC44?), but there's also a direct train to Zürich in the afternoon that may cost less (you'd have to pay the reservation fee for each train). You don't need a reservation for trains in Switzerland (without crossing the border).

Personal opinion: Don't do it. Switzerland has one of the best public transport systems in the world (you may find all public transport at sbb.ch where it is also possible to search for an adress), it's frequent, you don't need any reservations when holding a rail pass and to buy just more travel days when buying a railpass anyway might be much more cheaper than going by car.

Directly from Zürich, there's no private sleeper left (sold out), just single beds in 3 person compartments or couchette beds (both not private). There is availability for a private compartment from Basel SBB (one hour from Zurich).

You need to check all prices to be sure. And it depends. There are no fixed prices so prices are just true for the given momentan and may be different tomorrow. 

It's no problem at all. But it will be much more expensive doing it that way as prices are dynamic. There may be no cheap fare available when buying late. 

It does. You should buy normal tickets ASAP.

If you'd like to have flexibility, then a global pass might be the way to go. You'll need reservations but they have a fixed price and are much easier to get (of course when a train is sold out it's sold out). Only exception is the sleeper train that should be booked ASAP. When buying a cheap advance fare ticket, you get a fixed train. Compared to open tickets you should opt for a rail pass.

Thanks Hektor for your inputs- was really helpful.

From Zurich to Amsterdam, is it the same Nightjet 404 or a different train where i can get sleeper? Any particular site you suggest where i can book it?

And should i decide not to go ahead with global pass, then is there a single site where i can book all my train tickets instead of doing it in individual train sites? 

Thanks again

BTW: I did update the previous posting to clarify things (and did add my opinion regarding car renting in Switzerland). 

It's the same nightjet that gets more carriages in Basel SBB. Best way to book the night train is https://shop.oebbtickets.at/en/ticket (add your railpassed as reduction for both travellers before going to the ticket page if yo'll buy them).

It's always the best idea to buy from the original carrier. Otherwise you may try https://www.raileurope.com/ for the day trains (even for passholder reservations; desktop version only).

Thank again Hektor, got your point on renting car. Its just that wanted to book airbnb in a village and was worried on transit. But ya thanks will look into.

Will explore the links you sent, thanks again

Check Swiss timetables on sbb.ch. It contains all public transport.

One more question- once i buy Eurail pass, how do i book seat reservation? Again in rail Europe site or respective train/carriage site?

For your itinerary, Rail Europe is the best. You may add your railpass at the bottom of the page before searching for a connection ("add railpass"). 

I'd just book the sleeper train with the operator (ÖBB). 

I just bought Euro global pass and trying to book sleeper from Basel to Amsterdam, but the OBB site is not showing any such option. Only option it is showing is seat reservation. Can someone please guide me?

You can do it on the ÖBB website but it's easier on www.nightjet.com: add the Interrail/Eurail discount.

I assume you did choose “seat reservation only”? Then you’d get just the option to reserve seats.

You need to add your Eurail pass when selecting two adults twice and then proceed with “one-way tickets and day tickets”.

Pay attention to select the direct NJ, not any other trains. The reservation fee for a private compartment for two should be 289,80 €.

Yups, it says ticket not available. Guess only seat (seating) is allowed in global pass and cannot book sleeper/bed at discount with eurail global

But again, by choosing “book ticket one way” shows options whereas “seat reservation” shows no options for the same date. Guess global pass doesnt work for couchette/sleeper. 

You must add Interrail/Eurail as a discount and then select one-way tickets. It is the only way that works.

The price is different with or without the discount, you can check.

Night trains aren't exactly cheap, even with a pass.

Your screenshot does show that you did search for April 17th. There's no private sleeper compartment available for two.

You itinerary says you want to leave Switzerland April 18th - that's what I did look for. There's availability. 

But it also seems that you didn't add an Eurail pass as reduction for each passenger. 

Hi Hektor, yes my initial itinerary was taking an early morning flight from Zurich, but this night train looked tempting and went ahead and bought global pass. But unfortunately unable to book via pass, not sure where is the issue. Anyways thanks - will look for taking flight - maybe this time from Basel (easyjet early morning looks throwaway price)