I flew Manchester to Chicago with American Airlines last January and they were very good. The plane was no where near full so had lots of space to stretch out in (one bloke stretched himself out across four seats, strapped himself in and went to sleep). I had a connecting flight in Chicago to Louisville (Kentucky) also with American Airlines, which was great as after clearing immigration and customs just left my case with AA, just past customs and didn't have to lug it around when I changed terminals. I'm flying with Continental to Newark in December, I hope they're as good.