My wife and I will be in Paris next week and we'd like to get to Lisbon via train (we already have our Eurail passes). It looks like the only way to get there is via a night train, but I've heard that you're better off crossing the border into Spain and making your overnight reservations from a border town (like Irun) versus making them at the beginning point of our travel (Paris). Is this true?
Train companies limit the number of seats allotted to passholders. August is when the French go on vacation so trains going south from Paris can sell out. Popular night trains can sell out weeks in advance. For those reasons I recommend that you not wait until you get to Paris to make reservations on the TGV to Irun and that you not wait until you get to Irun to make reservations on the night train to Lisbon. Make them TODAY with Rail Europe and pay whatever it takes to have them mailed to you as fast as possible.