Quick answer: The best time to visit Mexico City is March–May (dry, warm). Expect a mid-range budget of about €70 per day. Visa: Visa-free for most EU/US/UK passports (up to 180 days).
Why this window
CDMX is a city of distinct colonias. Clustering by neighborhood — Centro, Roma/Condesa, Coyoacán — turns a sprawling megacity into a walkable plan.