I don't travel as much as I once did. However, when I am on the go I pack my 12-inch MacBook, some USB-C accessories, and the power adapter into a $64 Travel Express from Waterfield Designs. It's a rugged, good-looking case. Add the optional shoulder strap for another $22 as I have and you also have a protective carry bag.
What's more, the Travel Express is spacious enough to hold a cell phone and, if you really squeeze things in tightly (which I don't recommend), a magazine. Soft, microsuede, scratch-free pockets separate and protect each item, while plastic inserts protect the laptop and help maintain the Travel Express' shape. And it’s not just for the MacBook; the case works with any size of iPad, MacBook Air, and MacBook Pro.
A YKK, self-locking zipper opens the case along the top and side panel of the Travel Express, making it easy to access to the contents inside. Note that the zipper is sewn in a continuous loop all the way around the mouth of the bag, so there's still a small gap at the top even when it's zipped close. It's small, but big enough to let dust and water in.
Despite all its features, the Travel Express is relatively svelte though sturdy. And the case/bag has the usual top-notch stitching that Waterfield Designs is known for. The case is available in black ballistic nylon or waxed canvas.