One of the most important things when designing your home office is organization. Having you work space all cluttered makes for a very stressful work situation. No one wants to work when they have a million things cluttering their space. This is something I still struggle with even when the rest of my home is spotless. I never get much work done in my home office because its overwhelming.
When a couple lives together and both are working and need home offices, it is a good idea to split up the work space so that it is not too cluttered and things don't get mixed up.
Having separate areas for each person eliminates possible confusion and fighting. Both will have the ability to work at the same time if need be.
Some homes have enough space to dedicate a whole room to having a home office, other homes are limited on space and have to have little areas designated to be a home office. That doesn't have to be an unsightly thing though. There are creative ways to even "hide" your office space.
One way to do this is getting a piece of furniture made to be a desk that closes up to hide the computer and organization. This can fit in almost anywhere and when closed looks pretty.
Another place that people put home offices is in the attic. Since there is usually weird shaped rooms in the attic space that can't be used for just anything, people usually use that as the office. Home offices are a convenient thing to have in a home if you can make the space for it. Especially when they dont have to be big elaborate offices.