We haven't travelled by train in France for years, I usually rent a car. In May, we are going from Paris to Bruge, then Antwerp and finally Amsterdam. This time we want to use the train, or even bus, bus/train combination. I have checked Thalys but would appreciate knowing about other options if any exist.

The options from Paris to Brugge are TGV to Lille, then local train to Brugge (usually with another change at Kortrijk), Thalys to Brussels, then a local train to Brugge, or a through Thalys train. The Lille connections are hourly, Brussels trains are half-hourly, and the through train seems to run once a day.
From Brugge to Antwerpen, local trains are, I think, hourly as are intercity trains from Antwerpen to Amsterdam - there is little point in using Thalys trains for this journey.
Bus services, if they exist, would take a lot longer.
Train schedules are on www.bahn.de.

Unless Thalys is running a special, the cheapest route is GeoffHamer's first one, particularly if you book the Paris-Lille TGV well in advance (up to 90 days allowed) at www.voyages-sncf.com and get a PREM'S (discount) fare. Note, however, that SNCF has recently revised its Web site and you can no longer book PREM'S on the English version. You need to be able to handle French.

My previous post is incomplete. Persons using the UK version of the SNCF site may still get PREM'S fares, but they have to be retrieved in the UK. They can no longer be self-printed.

Thanks GH and TS - that is what I needed.