Here's a great tip from http://www.hinkleylighting.com. They are one of my favorite sources foe beautiful lighting.
One of the most important considerations when selecting a chandelier for a specific space is its size and placement. Since chandeliers are designed to command attention or be a focal point, it’s important to get it right. Here are some simple guidelines used by the pros:
When determining whether to hang a flush, semi-flush, or multi-tiered chandelier in your foyer, be advised that the bottom of the fixture should be at least 7’ from the floor.
For two-story foyers, if there is a window above the front door, center the chandelier so it can be seen from outside.
If your foyer is extra-large, you may also want to add sconces. Sconces should be installed 60” from the floor and 6’–8’ apart.