Jonathon Jones writes in the Guardian about the Four Seasons commission. He adds some detail, but comes to essentially the same conclusion as me; these were not "sombre, thoughtful" works (BBC), but angry, aggressive ones - in intention anyway:

"Sitting amid the buzz and excess of the Four Seasons, Rothko must have felt that he had been deluded - that the wealthy diners were not going to be harrowed. That art could not change anything. That his paintings would just be decoration after all."

http://www.guardian.co.uk/culture/2002/dec/07/artsfeatures

Maybe it's because I'm a Londoner - that I moved to Nice.