I have taken the Thalys train in the opposite direction - from Paris to Amsterdam. While I must admit to never investigating the flight options as booking from Australia as I figured there wouldn't be many, it probably would have been expensive in comparison, and the train has so many advantages.

As a group you will find it much more enjoyable for conversation! While I travelled solo on the Thalys to Amsterdam, I took a number of other long distance trains in France in a group of 4 and when we booked those tickets we could request a seating group of 4. This meant that we could share food, play cards etc all around a little fold-out table. I can't recall if Thalys had group seating arrangements however but it would be interesting to know...

And as another Ziner (or two) mentioned, the convenience can't be beat. You can stash your luggage overhead or under your seat and can pick it up and move straight away - no baggage carousel waiting. I had a framed backpack that I could just put in the overhead rack and my day bag between my feet. I don't recall running out of overhead room like I do sometimes in plane cabins, as there were other luggage storage areas elsewhere to take bulkier items. You rarely have to deal with airport traffic - the train pickup and drop-off is central (I was arriving and departing via the local train or metro system on either end).

The route wasn't particularly scenic if I recall correctly, but I had lots of leg room and could see terra firma if and when I desired! A point to note - if you have a preference with regard to smoking/non-smoking and direction of travel, do ask when buying your tickets - I get motion sick if I travel backwards so I could request a forward facing non-smoking seat when booking. :) Megan Brisbane, Australia