Essentials / Amsterdam
Amsterdam is walkable until luggage, rain, museum timing, or Noord enters the plot. Use the Schiphol train, understand Centraal, keep GVB trams in the plan, and treat the free ferry as normal transit rather than a novelty.
Essentials / Barcelona
Barcelona airport transport is simple once you stop treating it as one option. Aerobus is the easiest city-center shuttle, the R2 Nord train is the cleanest rail move if Terminal 2 or Sants/Passeig de Gracia fit your route, and taxis or Uber make sense when luggage, late arrivals, or awkward addresses start to matter. Use this guide as the practical decision layer: where to stand, which direction the stops run, and which timetable link to trust before you move.