While TOS Kirk obviously wore yellow (though I believe there were behind-the-scenes reasons for the color selection of the day), on the big screen I just can't imagine him wandering around in a yellow uniform.
Actually it was originally an avocado green velour that photographed as gold under the bright stage lights. Basically it was the same color as the wraparound green tunics Kirk sometimes wore, which were of a different material so their real color was more evident. I think that in season 3 they replaced the velour with a different material, but made them gold to match what the old tunics had looked like onscreen.