These machines are pretty well equipped, with a full complement of disk drives and ports, but they have somewhat less power than the true heavyweights. The best screens are made with a technology called TFT, and most laptops today have them. But in most cases, I think 12-inch screens are fine, and much cheaper. If mobility and light weight are important, you can do quite well with an 11-inch screen. This is a figure that governs how much material can fit on the screen, whatever its physical size.
High resolution can often compensate for a smaller screen.
This is a personal choice, but in general I prefer IBM's laptop keyboard to everybody else's. I also prefer the pointing stick, used by IBM and Toshiba to emulate a mouse, to the touch pad used by many others. But travelers will want the battery to last at least three hours. The very lightest machines tend to have the least battery life, because their size and weight require the use of smaller batteries. However, the Toshiba Portege 3480, which gets about 3 hours out of the box, can be enhanced with a large, high-capacity battery that fits under the machine and nearly triples the battery life.