I didn't care for 'wides', but find that I do like adding 'heights'; give a 'wall of sound' feeling, but i think this all depends on one's individual room. Mine is sufficiently narrow (14 ft) that the 'wides' were too localized, but deep enough (17.5 ft) that the 'heights' work well.
yea everthing depends on the room
have similiar space but much longer (34") so rears work really well
One thing I have found in set-ups I have heard - the better the position of mains
the less need for sides and heights -
nice imaging speakers placed well away from walls will give you that spatial imaging naturally
but having free reign on speaker placement is issue for some and I have heard wides/height work in those set-ups