In a renovation on the other hand we have to consider what effect a new skylight will have on the efficiency of the existing building. In some cases the additional sunlight (and therefore heat) can help reduce the amount of energy needed to heat the house. It depends greatly on the local climate but also on the design of the building envelope of the house.
Bright idea for unexpected lighting: Look for opportunities to install light fixtures in alcoves tray ceilings and wall niches to trace interesting lines. Notice the hidden lights in the ceiling alcove above the cylindrical fireplace mantel here.
Adding lights to stair risers is beneficial since it can be hazardous negotiating stairs especially at night. Staircases are often enclosed so light them from the sides or embed lights in the risers as a design element.