Moderator: American AAdvantage, Travel Safety/Security & Texas, FlyerTalk Evangelist
Join Date: Sep 2006
Location: AUS / GRK
Programs: AA, HHonors, Hertz
Posts: 13,485
I'm not sure who is telling the OP that, "all flights are full in business," but as someone pointed upthread, tomorrow's AA 734, PHL-MAN is listed as J7/C7. When you look at the seatmap on EF, it shows a fairly wide-open business cabin, with most of the middle section open and even a few vacant window seats.
I've done the train from Edinburgh to Manchester and I don't remember it being too bad; maybe 3 hours if I remember correctly.
If OLCI doesn't work for the OP's selected flights, I'd call and ask to be put on this one instead.