If you just want to see the flying display there is a football pitch next to the Premier Inn where all us locals go. Or there is a pub opposite Morrisons but its a bit further away.
I think Farnborough has suffered a double whammy, increased regulation of displays and increased development around the airfield. The last show had the Red Arrows just perform a flyby. Everyone thought it a waste of time/money, hence the cancellation of the public days.