Dining room lighting should:

Provide sufficient lighting for dining
Cast attractive light on people, silver, crystal, china, food and centerpieces,
Create a pleasant mood for social interaction, and
Provide sufficient light for other activities at the table or around the room.

Focus on the table.  Lighting in the dining room focuses on the table, usually with a central chandelier or pendant.  Any other general lighting in room should be soft, adding to the warmth of candlelight or the sparkle of the chandelier. Wall lighting makes the room seem larger and can highlight furniture such as a sideboard or buffet.

Flexibility.   Flexible lighting in the dining room permits you to use the space for many different activities, such as family entertaining, games, hobbies or homework. For this reason, one should incorporate general, area and task lighting into the dining room plan. This is best achieved with the use of dimmer switches.

Chandeliers.  Chandelier styles and materials are a matter of taste. A beautiful fixture should complement the decor and your own style.  
Size.  The size of the fixture depends on the size of the room and of the table. As a guideline, the diameter of the chandelier in inches should be about:
the  length of the room in feet plus the width of the room in feet or the width or diameter of the table less 12 inches.  
In rooms less than 10 feet wide, a chandelier should be less than 24 inches.   In rooms with ceilings of 10 feet or more, one can consider multitiered chandeliers.

Suspension Height.  Suspend fixtures high enough so that diners can see one another across the table.  If the ceiling is 8 feet, the bottom of the chandelier should be 30 inches about the table.  Add 3 inches to the suspension height for each additional foot of ceiling height. For example, 33 inches above the table from a nine foot ceiling.

Bulbs.  Exposed bulbs should range from 7 ot 25 watts.  Always provide general room lighting to supplement a chandelier with exposed decorative bulbs.  Chandeliers with diffusing shades can use lamps up to 60 watts.  Chandeliers should always be controlled by a dimmer.