Looking for a few things/ideas

Looks fun. You have no "one night stands" (except Luxembourg).
I am just concerned have you worked out how to do each journey?
Amsterdam>Brussels - easy, regular High Speed trains
"touring Bruges before arriving in Brussels" - implies yuo will have your bags with you in Brugge. Is this a problem?
Brussels > Luxembourg - regular trains.
Luxembourg > Avignon - a long train journey. Brussels > Avignon would be quicker.
Thereafter it is all long train trips.

You need to think of times and costs for your transport.

There is nothing wrong with what you have suggested but you need to work out the train logistics WAY before you decide if a EuroRail pass is cost effective. The pass is your last decision, not your first.

By rail question I mean -- don't think you can get from Amsterdam to Bruges without going through Brussels. So maybe a day trip to Bruges from Brussels would work better. Or storage you luggage in Brussels and then go to and from Bruges. Granada is not a good base to see Cordoba. Seville would work better. Getting from Spain to Lisbon can be a problem because the two trains systems are not well connected. Why be in Amsterdam for five nights and only one day in the city.? Stay in Bruges and day trip to Delft and Brussels. Time is on your side so spend some time with guidebooks, maps, and train schedules.

Shorter train connections if you go Amsterdam-Luxembourg-Brussles-Avignon.

I suggest you go on Mapquest.com and put in your cities. It'll tell you how far it is from one city to the other. You'll find that Spain and Portugal are very large countries, and such long train trips can be torturous.
If you travel Spain and Portugal, have you considered flying on a budget European air carrier, like Vueling.com?

We don't often see train passes being used by travelers online. Most go on individual train tickets or by budget air carriers for long distances.