A long sleeve dress in burgundy or plum works for dinner dates when the temperature has actually dropped and you need actual warmth. These colors in long sleeves read as autumn and sophisticated. The sleeve gives you coverage without adding bulk. Look for dresses where the sleeve is tailored enough to be intentional rather than just an extension of a t-shirt. A midi length with long sleeves feels complete and elegant. The fabric should be something that moves, not something stiff. These are the long sleeve dresses in deep jewel tones that work for dinner when you need to dress for the actual weather and still look like you made a real choice.