I've been to STN
more times than I care to imagine.
It's very good for watching the movements while airside - if you only have hang luggage you may stay there - but not that good landside. Your only real option is to leave the terminal, turn right and proceed to the bridge (very easy to find). From here, you get a partial view of the runway plus perhaps 10 stands. It's OK
, but not that good. You might get bored within an hour.
There's not much to do near-by, but London is only 45 minutes away by train.
I've been to BRS
probably 15+ times. There's no point going to the airport to watch the planes unless you have a car, for there are very few landside views and virtually the same while airside. If you do have a car, and I doubt you will, then there's a superb area a few minutes from the terminal. I won't go into details about that as I assume you won't have a car (ask me to tell you if you do).
"Everyone writing for the Telegraph knows that the way to grab eyeballs is with Ryanair and/or sex."