When hanging a light over a table or a kitchen island 28 to 34 inches is the recommended distance from the bottom of the light to the surface of the table or island. However the size of the light makes a difference. In general a smaller light can be moved lower and a larger light can be moved higher.
The light fixture should not be your only consideration — the type of lightbulb is equally important. Halogen compact fluorescent and LED bulbs come in a range of warm or cool hues. Much like the color of your walls the type of glow you want is mostly a personal decision. If your walls are covered in cooler tones you might want to warm them up with a lightbulb that casts a warm glow. Conversely you may want a cooler glow to brighten up a darker space.
Adding lights as decorative elements helps set a mood in a space. Provided that general lighting is already installed using lights instead of wall art can be a decorative way to provide ambient lighting.