Tom Bihn Cache & Brain Cell
The Tom Bihn Brain Cell and Cache are two excellent options for keeping your MacBook Pro safe. I've been using the Brain Cell inside of the Brain Bag for years and love the protection that this sleeve and bag combo provides. The newer Cache is a slimmer sleeve with protective foam that easily slides into another bag.
I love the Tom Bihn Brain Bag because it adapts to what I need to carry, and I can swap out the Brain Cell from a 13-inch for a 15-inch when I decided that the 15-inch MacBook Pro is what I needed. The Brain Cell snaps into the bag, but you can also remove it to carry the MacBook alone using just the Brain Cell. This sleeve offers hard sides that keep your MacBook Pro safe in transit. You can also clip a strap to this sleeve.
The Cache is slimmer and a better fit for users who need less protection as they go to work or around town. This includes .25" thick foam padding and works alone or can snap into many of the bags that Tom Bihn sells.