The new breed of business case is built to haul high-tech gizmos and double as an office. Business cases are typically made of leather or ballistic nylon. Microfiber, which is lighter and smoother than nylon, is growing in popularity for bags made for women.
Leather looks nice, but it's heavy, which is becoming more of an issue as bags balloon in size.
Leather bags are also more subject to damage than their synthetic brethren. Consider a case that comes with a removable sleeve designed to keep your laptop nice and snug. As anyone who carries a computer case will tell you, they can get heavy. If stress and strain is an issue, consider buying one that comes with a shoulder strap designed to relieve the burden. If you need more compartments for the gear you carry, you may want to look at a business case known as a messenger bag, or its larger cousin, the mobile office.