there are times when you'd plan to go out for dinner/drinks after work. and some (like me), are just too lazy to change from office clothes to an after-office attire. at times like that, i'd make sure i would wear something that wouldn't look too casual for work and too formal for a night out. a jacket/blazer over a simple sleeveless top and a pair of jeans made of soft fabric and a very comfy high-heeled sandals would be my best bet.
after office, you can just take off the jacket to look a lot more casual for a dinner-movie date with your girl friends