We are planning to visit in June, and I'm wondering about the mechanics of taking the train from Amsterdam, stopping off in Brussels for a few hours, and then heading on to Paris. We weren't planning on having rail passes as this is our only rail journey on our trip. Do you just buy tickets for both separate legs of the trip? Any help or suggestions of where to look are appreciated.
Yes, you have to buy separate tickets to make this stopover (this was not always the case, but is now). For tickets from Amsterdam to Brussels, use http://www.nshispeed.nl/en. Use Amsterdam Central and Brussels Central as your stations. You'll see that some runs involve more or fewer changes, and some explain that the ticket is good on any train (i.e, it's unreserved) while others (the ones that use Thalys - see below) are only good on that particular train. If you book far enough in advance and can commit to a specific train, I see that the Thalys, which is faster and easier, can also be cheaper. But the Thalys uses "airline pricing." This means that tickets are reasonable if bought in advance as non-exchangeable and non-refundable, and become MUCH more expensive closer to travel. It also means your ticket is for a specific train; you can't just take any train on that route.
For Brussels to Paris, use https://www.thalys.com/be/en/. Use Brussels Central and Paris Nord as your stations. Again, the sooner you book, the better the price; but don't book until you know exactly which train you will take, as you are then committed to it.
For your Thalys tickets, you can print them at home. If you are not taking a Thalys from Amsterdam to Brussels, you can buy the tickets when you get there, as their price doesn't change.
Harold, thank you for the great information.