How low should a chandelier hang?

A chandelier hangs 30"-32" above the top surface to the lowest point on the chandelier. 

How wide should a chandelier be?

Proper scale is 2" per foot of a room. 
For example, the circumfrance of a room is 12'x14x, then the perfect width of the chandelier is 26" wide.

How wide should my chandelier be?

If your table seats 4 people, your chandelier width is 20"-24".

If your table seats 6 people, your chandelier width is 25"-29".

If your table seats 8 people, your chandelier width is 30"-36".

How low should a chandelier hang with a two-story ceiling?

The chandelier should hang 10'-11' above the floor.
Fan Size:
Rooms up to 75 square feet, like a bathroom, do best with a fan 36" or smaller. 
Medium sized rooms up to 144 square feet can fit ceiling fans from 36"-42". 
The larger bedrooms & family sized rooms around 225 square feet are most efficent with fans that are 50"-54".

Ceiling Height:
Place the fan higher than 7 feet above the floor in the middle of the room. Optimal placement would be either 8 to 9 feet from the floor. 

Damp Locations:
Fans to be used  in bathrooms should be specifically designed and approved for damp locations. 
Want a fan for the patio? Opt for a fan that is UL-listed for wet locations

Ceiling Fan FAQ's