i've also flown between the US and Europe a lot, 20 times at least in the last 10 years.
Dali is mostly right on, but i think price is less predictable than the pattern he paints. i've seen prices from the same airline drop $200 overnight, then shoot up again a few days later for no apparent reason.
if you're willing to pay the current price, just buy it and don't look back. it's never cheap to fly overseas! you
might end up catching a last-minute deal if you wait, but you might also see the price increase dramatically. just no way to know.
as for where to book - i tend to find the best prices on the actual airline's website. and don't forget to look around - BA often has great prices for trans-Atlantic flights, but their service tends to be pretty mediocre. i'd say i miss my connecting flight with BA 3 times out of 5 because of delays.
i've had good experiences with KLM, though they don't always have seat-back video screens, which is a must for a 7 hour flight!
anyway good luck and have fun
