Don't ever park at London City to collect someone. Make them ring you when they've cleared the terminal building, and then pick them up. The costs are worse than being burgled!
London City not too bad, just be sure to read the signs before you enter the car park. Basically use the right hand car park (long stay) as you drive in. It's been a while since I was last there, but iirc, it was cheaper to buy 3 hours parking than take a chance in the short stay one.

Just checked...
Short stay 0-30 £5.50
30-1hr £10
-2hr £14
-4hr £18
Long stay -4hr £16
the biggest problem is that alot of the flights into city are less than 45mins, so you have to set off before the flight does, and only find out it's delayed when you get there

Have spent 5 hours at T5 when a Police Incident, (they were using the helicopter to shoot a fail-to-stop on an industrial estate just north of the airport), closed the both runways about 2 minutes before the flight was due to land. Passenger went to Stansted before returning to Heathrow at about 1 am.
Airport parking and meeting people in the terminal is sooo much easier, it's just a shame that they feel the need to bend everyone over for the privilege.
Doesn't help that some airports have farmed out their carpark management to idiots such as NCP, who having been lumped with tired and neglected carparks have to not only manage them, but also get them up to scratch in the first place, and sadly that costs
