The thing that actually changes a first week in Spain is the clock. Lunch is late, dinner is later, and a square that looks empty at five is the evening. Shops still pause in the afternoon in many towns, even if the big cities have softened that habit. Spanish is the public language; Catalan, Galician and Basque are not folklore, they are what you will hear and read on local signs depending on where you land.
The peninsula is high in the middle and hot in summer. Madrid and the meseta are not the same climate as Galicia or the north coast. AVE trains connect Madrid with Barcelona, Seville, Valencia and other large cities in a few hours. The islands are a different logistics problem: ferries and flights, plus a car if you leave the resort strip. Andalusia, Catalonia, the Basque Country and the two archipelagos do not add up to one mood.
English is workable in the tourist belts and thinner inland. Cards are widely accepted. Late eating is not a performance for visitors; kitchens really do sit that way. A first trip usually holds together if you pick a region and a couple of cities, not a loop that treats the whole country as a corridor between beaches.
