I'm backpacking through Europe in May/June 2011, and for some parts of it I want to sleep in an airport. This would only be in cases where I'm spending one day in the city, because:
-I want to see as much as I can in the one day that I'm there, and therefore I'll probably be out exploring late
-I will be getting a train/plane to my next destination early the next morning, so I will have to wake up early to make it to the station/airport
-If I will be out late and I have to get up early, I'd rather not go through the trouble of booking a hostel and have to waste my cash to pay the balance, when I'm hardly going to be there anyway (Assuming I'm were to get back at midnight, and I wake up at 5 to leave my hostel at 6, it would only be 5 hours of sleep...not worth paying for the hostel when I could go somewhere else for the "nap," as it really isn't a full nights sleep)
The cities in question are: Zurich, Pisa, Milan, Rome, and Madrid. I have plane tickets for Rome-Madrid (flight leaves 9 AM) and Madrid-New York (flight leaves 10:30 AM), so I will have proof of a flight and shouldn't have to worry about sleeping there and being stopped by security if they wonder why I'm there.
I have train tickets for Zurich-Munich, Pisa-Milan, and Milan-Venice, all between the hours of 7 and 8:30 AM. However, I feel like an airport would be a safer place to sleep, and would rather stay there for the night instead of a train station if I decide to forego a hostel.
I will probably end up getting a hostel in Pisa (I am arriving in Pisa at 4:30 PM, and leaving at 7:30 AM, and since it seems like there isn't much to do, I might as well get a hostel, try and get to bed early, and rest up). But if I sleep in the Zurich airport and then go to the train station for my train, and if I sleep in the Milan airport and then go to the train station for that train, will I have an issue not having a plane ticket? Will they kick me out? Or does security tend to leave everyone alone? I just don't want to be in a situation where I get into some sort of trouble for not having a plane ticket if I am asked to show one and I don't have one.
I've been on the sleeping in airports website, so I've read reviews of each of the airports in question, but I just want to have information pertaining to people without plane tickets who just want to sleep and leave.
Any tips, advice, or information would be much appreciated