Use a bag such as this one to make your commute to work a bit easier. It only comes in one colour, black, but it does look quite neat.
From OnBuy
Thule Subterra TSSB-316B Black notebook case 39.6 cm (15.6") Briefcase
Ecprof
3204085 - THULE SUBTERRA 15 MACBOOK
This product is also available at 4 unverified stores.