A floor lamp nestled against a window is a smart substitute for daylight so that when the sun goes down an ambient glow will pour in from a similar direction to balance the central light overhead.
The most common use of up lighting is in a recessed cove around the top perimeter of a room. To maximize light output use a T5 fluorescent or LED light source that will wash the ceiling with light. This helps to create a brighter ceiling that bounces and reflects light throughout the space without glare. Combine this with lots of natural daylight to increase the overall light levels in a room.
Instead of or in addition to sconces hidden lights can add a general glow that bounces off the wall and into the room in an even subtler and more diffuse way. Cove lights are built into niches that hide the light source (often a plain LED strip) but hidden lights can also be obscured by medicine cabinets shelving or storage units.