Welcome & Bienvenido/a to Flyertalk
SantaMonicaTravel!
If you can find a reasonably priced flight to LCY that suits you, then by all means take it. You won't find many people arguing that this isn't the best aiport for access to the City of London.
Unfortunately, there are only two flights a day and BA has a monopoly on these.
For most of us who fly between London and Spain costs and times are a factor. Personally I prefer evening flights as I can maximise my time in Spain that way.
London is a big place and there is no definitive answer to your question without knowing where you are planning on staying. Yes, LCY is best for the City of London, but the actual City is the financial centre, is only 1 mile square and is towards the East of London. Apart from Tower Bridge and the Tower of London and a few other tourist attractions, there is not that much for visitors and most head for the West of London which has more entertainment and shopping options.
If you wish to base yourself in the West of London then
Heathrow might be a more sensible choice as there is a fast rail link which can take you from LHR to Paddington in 15 minutes.
Another popular base for tourists is the Victoria area, just to the South of Paddington. If you are planning to stay here then
Gatwick airport might be the best airport for your needs. There is another high speed rail link between Victoria station and LGW that takes 30 minutes.
If your own definition of 'best' has anything to do with price, then both Luton and Stansted airports are workable alternatives. It is possible to get from Victoria to Luton or Stansted for £2 using
www.easybus.co.uk
Baker Street to Luton takes under an hour. The trip to Stansted is roughly half an hour longer.
As there are so many variables involved (for instance where you to stay in the Chelsea/Fulham area then Gatwick might be the best airport as there is a direct bus from LGW to Fulham Broadway) unless we know where you were planning on staying in London there is no definitive answer. What is best for someone else might not be best for you.
Here is a very useful thread from our UK forum which explores this topic more thoroughly.
http://www.flyertalk.com/forum/u-k-i...n-sou-mse.html
MY OWN ADVICE TO YOU as you are only going to be in London for a short time is to choose, if possible, the same airport to fly into London as you will be using to fly out. That way you can store the bulk of your suitcases at a Left Luggage facility and thus eliminate the need to go lugging them around with you.