Who do the cheapest flights to USA from london? and whats the best US airport to use for the cheapest flights? im looking for a months holiday and the cheapest tickets to any US airport thanks.
Hard to say that 1 is always cheapest — airlines usually match prices, so when 1 announce an offer, the rest quickly follow. New York will likely be the cheapest arrival point, simply because that's where the most competition is for flights to/from London. Sometimes Kuwait Airways or Air India are cheapest, sometimes Zoom or Virgin; sometimes it's cheapest to book direct from the airlines, sometimes a consolidator has it cheapest. I would shop around using these:
http://www.cheapflights.co.uk/flights/New-York/London/
http://www.farecompare.com/maps/myAirportCategoryMap.html?departure=LON&category=Domestic
http://travel.kelkoo.co.uk/c-172201-flights.html
http://www.bookingbuddy.com
For example, I see one for £263 return (total with all taxes and fees) Sept 2-Oct 2 found with Bookingbuddy.
For a month's holiday, however, you might also consider http://www.flyzoom.com to Fort Lauderdale or San Diego. £328 similar dates to/from FLL, for example.