I have just booked from Edinburgh to New York for £271 return in October.
Started looking via
www.travelsupermarket.co.uk and played about with dates until found the best price which turned out was through Expedia. Then went via quidco and booked flight and hotel together.
Flights are with KLM/Northwest via Amsterdam but thought if you have to go via somewhere (direct flights are too expensive for my budget) then I wasn't really too concerned where it was via. - you could get a cheaper flight from London I guess but you would still need to get there.
Actually just came back 2 weeks ago from my first trip to New York did the same flights and hotel (with sister and daughter) and couldn't resist another trip with my partner as he has never been.