Bigger screens allow you to expand the size of text and pictures to make them easier to read, and they also make it possible to open more than one window at a time. Therefore, conventional wisdom says that you should get the monitor with the biggest screen you can afford. True enough, but there are some exceptions.
First, consider the trade-off between the size of a screen and the cost of the monitor. If you spend a lot of time sitting in front of your computer screen, a slightly smaller but higher-quality screen could be the better choice because the smaller screen could be sharper and brighter and less tiring to use. Buying the least costly big monitor you can find is often a poor way to save money.
There's a practical limit to the size of a monitor screen for home or office use. Anything larger than about 21 or 22 inches is likely to be extremely expensive, and more appropriate for a public display.
Second, think about getting two medium-size monitors instead of one big one. Or if you can afford it, add a second large monitor to your existing setup. Multiple-monitor operation can be a lot more flexible and productive than putting everything on a single screen.
Chapter 28 explains more about setting up multiple monitors for your computer.
Third, a smaller monitor screen can have some benefits that have nothing to do with the performance of your computer. If you're setting up a computer on your kitchen counter, or in a corner of the living room or bedroom in a small apartment, you might not want a big screen to dominate the décor of the room.
Finally, remember that a laptop computer with a bigger screen must also be wider and deeper than one with a small display, even when it's turned off. A smaller laptop may fit into your briefcase or backpack more easily and it takes up less space in cramped areas like an airliner's fold-down tray table or a college lecture hall.