I've done ORD-LHR in Y and it wasn't so bad when I had an entire row of 3 seats to myself and could lie down (with some discomfort). Glad it was only a 6-7 hour flight, so I got by, but business class is definitely favorable. This was purely due to project budget constraints. Otherwise, my company's policy is J for overseas travel of 5+ hours (mainly to ensure the NYC-LON flights for execs qualify), regardless of level. We do have to use preferred airlines, where possible, but there are no rules about having to take lowest fare, connections, etc, although everything goes through at least 1 level of approvals and have to enter business justification (from drop-down).