going through France

Strasbourg together with Colmar (easy connection to Amsterdam via Karlsruhe and ICE :) )

Avignon with a daytrip to Marseille ;) (usually one direct Thalys to Amsterdam in Summer) otherwise direct TGV´s to Brussels and then with reservation free IC further to Amsterdam :)

I’ve got a feeling the Interrail pass might not be valid on these special ‘Thalys Sun’ long-distance services, but can’t remember where I heard this. Hope I’m wrong though!

Strasbourg is an excellent shout, but to avoid expensive reservation fees, make sure you cross the border on a regional train. By far the easiest way to do this to get to Amsterdam is to take a mid-afternoon regional train to Offenburg, then change onto the daily direct ICE from there to Amsterdam, which arrives around 10PM.

With France, many non-high-speed lines only see very slow and infrequent service, but if you don’t mind the inconvenience of a few long changes, there are some great secondary cities to see off the beaten track, like Albi for instance:

You're correct. There is no pass fare for Sun Thalys (or Snow Thalys):

https://public-pf.b-europe.com/nl/Producten/Details?id=c597a98b-d445-43d0-93d1-c1f304657f30

Thanks for that Info i messed up as i could use it with FIP i assumed Interrail/Eurail will be possible to :)

Means for Thalys count´s the same as for Eurostar  the Pass is onthem valid just on the “Normal Services” to Paris :/