Madrid Airport

I don't know the airport well enough to give you direct help. But those who do know the airport will need to know which terminal you are arriving at and what time, and which terminal you are departing from and at what time.

Madrid airport is HUGE, and has two sets of terminals. You can walk between terminals 1, 2, and 3, and terminals 4 and 4S are connected by a shuttle train, but you have to take a bus between the 1-2-3 complex and the 4-4S complex.

Thanks. I arrive at Terminal 2 and depart form Terminal 4. My luggage will be checked through to home. Will I have to go through customs when I change terminals?

I cannot speak to Madrid, but had one of those in Amsterdam last summer. Decided just to tough it out in the airport. Prior to my trip I downloaded a book. Got into that book. Found a Starbucks😀 Explored the restricted area. Got a ride in a security vehicle....no issues.....just some friendly customer service by security. People watched. Journaled some of my travel experiences. Messaged everyone of my FB friends 😂😂😂😂😂...ok, not really.

My plan got an extra day in Vienna prior to my initial departure with no hotel charges. Saved about $400 in airfare.

Amazingly about 4:00 a.m. the airport began filling up with travelers.

I would do it again if the logistics/cost saving was the same.

Amsterdam had a restricted secure area where overnighters could stay. If you left the secured area you would have to leave the airport. It was possible to book a sleeping cubicle....but that’s not for me.😳

Again....not sure about Madrid.

I've no direct experience with Madrid Airport, but there appears to be a in airport hotel in Terminal 4 outside security. https://www.hotels.com/ho476789/air-rooms-madrid-by-premium-traveller-madrid-espana%5D%5D?pos=HCOM_US&locale=en_US It gets mixed reviews and it isn't cheap.

If sleeping in the airport is forbidden or it closes in the wee hours, I'd get a hotel with shuttle.

If it's not forbidden, I'd do what I've done on nasty layovers in the U.S. Eat quick before the real resturants close. Buy snacks before shops shut. Walk a lot. Read. Sketch. Edit photos. Make sure your personal item makes a reasonable pillow. Loop your arm through it when you sleep. If there are pay showers, use them. Get breakfast.

...Will I have to go through customs when I change terminals?... Depends on where you are coming from. From within the Schengen zone -- no customs. Security when you change terminals and Passport control if you are returning to the US.