Verdict first: Lisbon for a tighter budget, hills and old trams; Barcelona for a denser food scene, nightlife and an in-city beach. Lisbon runs about 30–40% cheaper (€60–80/day) and suits 5–6 days; Barcelona costs more but offers more variety and suits 5–7 days. Barcelona highlights: book Sagrada Família and Park Güell tickets well ahead (or risk multi-hour waits); the Gothic Quarter and Barceloneta beach are walkable. Avoid staying near Las Ramblas — Gràcia, Poble Sec or Sant Pere feel closer to Lisbon prices. A flight between the two takes under 2.5 hours, so a split trip is easy.