There are trains from Gare du Nord to Brugge every half hour. Because they are either TGV or Thalys, reservations are required. I am assuming that there's absolutely no reason for me to get the reservation before getting to Europe, since there are trains every half hour. For the record, I could be flexible within a couple of hours of my desired departure time (thus, that means I could aim for 5 different departure trains).
Marshall, I have no personal experience with this, but I think this is a good assumption, especially as you're flexible with time.
We reserved out seats when we arrived in a city for our travel day.
I assume that you will have a railpass. If so, you will have to buy a special passholder fare ticket for 26-33 euro if you take a Thalys train from Paris to Brussels. No reservations are possible for the IC trains between Brussels and Brugge.
The route that starts with a TGV goes to Lille. The reservation fee is 3-5 euro. No reservations are possible on the IC trains you will take from there to Brugge.
"No reservations are possible for the IC trains between Brussels and Brugge." And no need for them either. There's at least two IC trains per hour going in that direction and there's never an issue finding a seat.
PS- Thalys doesn't service Brugge directly.
I think I'll aim for one of the TGV routes through Lille, since the reservation fee is waaaaaay cheaper.
I was aware that the IC trains don't require reservations. I am trying to avoid the Res Req routes when possible, but sometimes you can't avoid them.
To the responder above: Yes, my wife and I will have a saverpass.