Do you expected your travelling employees to
(a) work on board
(b) come into the office fresh as a daisy at 09:00 having landed at LHR at 06:00 and then put in a full 8-10 hour day
(c) go straight to work immediately they have landed at their destination (outbound from LHR) and then put in a full 8-10 hour day
(d) travel with overnight case, laptop, briefcase
(e) arrive at either end in a suit that doesn't look like the wearer has slept in it for several nights
(f) have a happy employee who feels valued & appreciated by his employer?
then the answer is business class all sectors.
Otherwise just stick the poor scmuck in cattle-class.