If you're airside for a while and want somewhere to watch aircraft from, Cafe Amato has a grandstand spot. In T5A (main building), gate level, southeastern corner. It has a handy bar with stools facing in exactly the right direction; from the far right hand corner you can see all the way to the end of 09R/27L.
I can't say anything about the quality of the F&B, though, as I have so far only been able to try this during one of the trials trial.