I'm a big fan of Arc'teryx gear and they have new line of convertible luggage. Right now they're only on their LEAF (Law Enforcement Armed Forces) site, not sure when it'll be on the consumer side. The dimensions aren't on the site but contacted customer service to get them.

Covert Case C/O (carry on) - 40L, 35oz, US$179
http://leaf.arcteryx.com/Product.aspx?EN/Mens/Packs/Covert-Case-C-O
per CS: 21.5" x 12.5" x 10", 44 linear inches

Cover Case I/C/O (intl carry-on) - 50L, 41oz, US$199
http://leaf.arcteryx.com/Product.aspx?EN/Mens/Packs/Covert-Case-I-C-O
per CS: 23" x 13.5" x 11", 47.5 linear inches

Pricing isn't that bad for Dead Bird gear and weight seems really reasonable for structured/padded bags. There's internal tie down straps, but i think some ultralight packing cubes might be neccesary. I really like the organization of my Patagonia MLC but i might give the C/O a try.

This article has some views of the backpack straps and the interior:
http://soldiersystems.net/2012/06/09/sneak-peek-arcteryx-luggage/

The Blade 30 looks like a good option for travel. A full 30L bag with a laptop compartment.

Arcteryx sells higher-quality products. Likely these bags are no exception.

The only issue I see with the Covert Case C/O would be its somewhat thicker cross section, 10.o inches by 12.5 inches. That depth might interfere with their fitting into the overhead bins of a "regional jet" or similar plane, such as a Bomarider Q400 twin turboprop, though for a full-size jet, Airbus 320/321 or Boeing 7N7 there should be a problem.

(N = 2, 3, 4, 5, 6, 7 OR 8...)