I didn't chime in yet, because I don't have a MBA.
I bought an EE netbook before the MBA came out, it replaced the iBook as a traveling laptop. The iBook, an not much else than its power supply, fit in a Large Cafe Bag while inside a Cache.
The EE netbook inside its Cache is a perfect fit for the Large Cafe Bag and the FJN (Field Journal Notebook) and many other things.
When I travel with my husband, he carries the netbook in its Cache, power supply for the netbook, mini headphones in a one of my Large Cafe Bags ( I need to get him his own in Steel). The setup is stowed under his seat next to his food from the airport.
This way his Brain Bag can be stuffed with his clothes and... some of mine, shhhhhh. :)
This is the perfect setup as he can play, as much as he wants, with the computer at the airport or on the plane without dealing with the Brain Bag which is safely stowed in the overhead bin.
The Cache is a perfect fit to the Large Cafe Bag, yet has enough wiggle room that the netbook can be removed leaving the Cache in the Large Cafe Bag, very handy during meal or snooze time when the netbook can be quickly slipped in his Cache, the flap closed and the LCB buckled then stowed.
I also have a couple of Swifts, (I am not responsible for the fact that TB makes so many yummy colors which happen to match my yarns), I love them but I would not consider them for air travel, they have been part of many car trips and metro/bus commutes very successfully.
Get the Absolute Strap with your LCB.
My plane trip LCB is usually around 10 pounds, I can run with it and a Brain Bag without trouble.
When I go around town my LCB is less full but no matter what, I can't feel it. It never happened before with any other substantially packed bag.