Remember in grade school when your teacher explained to you the KISS Principle? No, not the best way to smooch (at least not until you get into high school) but keeping things simple. KISS, as I was taught, stood for "Keep It Simple, Stupid." While I never considered how inappropriate that phrase was (only with the additional word, 'Stupid'), it does bode well as a general principle to most things in life.
Things like packing for a trip for instance; in particular packing for a short, 3-day business trip. Long trips can be easy as you have a much larger suitcase to deal with and you can include many more wardrobe options. But when you're flying to a destination with just your carry-on, you better keep it simple.
I typically go with timeless pieces - you don't want to go too trendy as you are meeting with colleagues and most likely your boss (and if you are the boss, more reason to dress like you own the role). I also go with pieces that can mix and match well. Basic white blouse, black pencil skirt, and grey one-piece shift dress are absolute staples. Throw in skinny jeans, a comfortable stiletto ankle boot and a black leather jacket, you're ready to board.
My carry-on is a white Rimowa with four wheels that roll comfortably on any floor surface. Topping it with my Louis Vuitton Neverfull tote (mine's the GM (large) but you can go smaller) which houses my laptop and iPad, headphones and other accoutrement. And that's it. It really doesn't get any simpler than that - it's not trendy nor exciting but it's simple, timeless and efficient. That's what you want whenever you travel.