Is it doable? Is it worthwhile?
It’s certainly doable. Whether it’s worthwhile depends entirely on you and your interests. What attracts you in Antwerp?
I am a big fan of Antwerp, and feel that it has more than a full day's worth of attractions. I always have my doubts about people thinking Amsterdam is next door to Brussels. But Delft is a little closer. However, Antwerp is a major secondary rail hub, and there might be a faster train direct from Amsterdam. (I haven't checked.) So a different itinerary might be more efficient, depending on your overall trip. Reading between your lines, I would point out that Gent is at least as nice as Delft-if slightly less historic, but Antwerp is much bigger than either of them.
Note that no one at home will ask you about Antwerp! They will ask you if you went to Brugge, which is much farther on the train. I think Brugge is best visited as a daytrip from Antwerp-sleeping, but many posters here consider it essential to overnight in Brugge. I don't agree, and I've been there on a daytrip from Antwerp twice.
If you do take a train that goes to Brussels and not to Antwerp, there are about six trains an hour from all three Brussels stations to Antwerp, unreserved seating.
“ If you do take a train that goes to Brussels and not to Antwerp, there are about six trains an hour from all three Brussels stations to Antwerp, unreserved seating.”
Tim can you please explain what you mean by this? Brussels is further south from Antwerp. Every train from the Netherlands, the highspeed Thalys as well as the regular Intercity train, will first call at Antwerp before continuing on towards Brussels.
There are no direct trains from Delft to Antwerp. This journey requires a change in either Rotterdam or Breda.