The interiours of Singapore Airlines are very nice, with a lot of colours in Economy class and use of wood(!!) in First. Flying in first looks like sitting in a Rolls Royce !!
Virgin Atlantic is also colourful, with all red seats, but after 8 hours, it bevcomes very irritating and hurts the eyes.
Sabena has nice interiours, with blue leather seats (Also in economy) in their new Intra European fleet, and in their Wide bodies and older narrow bodies, the interiour is designed by the famous painter Magritte.
KLM is very dull, as is BA.
Lufthansa is disgusting, with yellow and grey seats that blind the eyes UGH!!!!!!!!!
AA in First and Business is good with woolen covers.