Well, sometimes Ryanair lands at apts that are far away from the major cities, but I do not think this is 100 per cent negative.
You have always to consider your TTT - Total Travel Time, and not always you are heading for Piccadilly Circus, but it might be you are heading for Cabmbridge ...therefore STN is your right choice.
If you are heading for Milan, the perfect choice is LIN, but BGY is generally better than MXP. The distance from the city center is the same.
If you are heading to Rome, CIA is nearer tha FCO, and you get out from the airport in 5' without walking for miles.
GRO is also your right choice for Costa Brava, and so on ...
their advertising ... why don't
life is sometimes boring and MOL knows it!
