In the category "covers protecting against shocks", you will find soft covers, such as "Be.ez LA robe" Low Resilience Polyurethane made (LRPu), which has the particularity to slowly regain its original shape and therefore absorbs shocks very well, or the "Case Logic LAPS113K" neoprene meanwhile, is a softer material and therefore seems less protection.
The LRPu indeed has advantages over more traditional neoprene He has great compressibility capabilities, damping, energy absorption and vibration (for shock), it is flexible, lightweight, with low conductivity thermal acoustic (it insulates sound and heat clear) and and low transmission of water vapor. Finally, it is resistant to mold. In short, it is the ideal material for protective covers, and so I would suggest rather that the covers in LRPu neoprene.
The rest is mostly a matter of size and taste: The Be.ez LA robe are available in many colors and sizes (11, 12 and 13 ", as well as 17"), where d others are in the dark or a little sad graphite.
The Be.ez is cut for macbook but you can of course drag other ultrabook there, just check the dimensions of the cover and your laptop before launching.
Finally, protecting but also less flexible; therefore less convenient but this remains a business use, you will also find semi-rigid covers like Case Logic QNS113K that perfectly well, but we also protect it harder to fit in a backpack or briefcase. But if you want more than a bag cover is in my opinion the best choice.