I've always liked "The Longest Day", it's really good if you are in the mood for a longer sitting. Once the action gets going it's really good for it's time. They used every trick they knew about cinema. That single shot scene with the French commandos attacking that building was really impressive. That must have been really difficult to shoot and it looks authentic too. Of course you can't go wrong with the old school sound effects of machinguns and explosions adding to the mix. They had all sorts of big name actors too. Another favorite of mine is "Von Ryan's Express". Frank Sinatra plays as a American pow who leads escaping pows using a train. They have to trick gestapo agents and avoid even friendly bombers to make the break to safety. I won't spoil the ending, I thought it incredibly fitting.