I have to agree that Cafe Amato seems to be the place to sit out those long waits. On "normal" days not many people discover it so it's a quiet and relaxing spot with reasonable food & Drink plus a great view.
I last went through in late April and T5 was nicely quiet after the fiasco of the 1st week - mind you all the gents loos in T5A were a disgrace (unclean, non-functioning, etc - thought I was back in T3 for a moment). Come on BAA - surely you can do better than this! 3 out of 5 ? No - I'll give it a 4 since I also experienced T2 @ Frankfurt on the same trip. T5 was on a different planet after that!