I am the CTO for CalFinder a contractor referral service like no other, and I'm very proud of that. I've been working in the construction area for only a short time and am finding that the people, whehter it be a homeowner, or contractor, are refreshingly genuine. Other than work, getting outside and fly fishing is the only way to go. Traditionally the attitude has been that bigger is better. Everyone wanted the biggest house with the biggest rooms that used the most electricity. For the most part, design choices for small rooms were largely ignored. Oh but times have changed. The focus has switched to paring down energy usage and wasted space. The focus now is on do a lot with a little. And quality design and energy efficiency begin with the windows.
Windows do wonders in adding expanse to a small room. They draw the attention away from the size of the room and the outer world where everybody's room is the same size. Therefore, lots of windows without a lot going on are the best choice. Think open panes and wide panoramic windows. French or sliding-glass doors are a rule for small spaces. In order to make a room feel bigger you bring the outside in to get a larger room and save on electricity with all the daylighting you've added.
While you want to keep things fairly simple in a small room situation, that does not eliminate creativity. Instead of one wide picture window you could choose several narrow windows side by side, wrapping the whole room in light. Skylights of course are always excellent for allowing natural light in.
Window style is important as well. The window market today has a lot more to offer than old wood and aluminum windows. Affordable vinyl is the popular option. Newer wood windows cost more but look great and are very energy efficient, nor are they all grid-paned anymore. There are also many shapes such as arched windows, diamonds...trapezoids? Well, maybe not on the shelf, but custom windows can be built and delivered faster than ever. Your window replacement contractor will be able to find answers regarding your many window options and what is best for your situation.
If anything, the only problem with window choices for small rooms is that there are too many choices. Just don't forget that, while the windows are a big factor in small space decorating, they are not the only one. Be sure to use bright paint colors, mirrors, and other such devices to finish everything off.