Frank Lloyd Wright's interiors didn't always go for the very high ceilings (prairie school, at least) but some of his Hollywood homes did use 10 foot plus drop rodlamps in the grand entrances.
Ebay occasionally has some examples of the rod type with a large-enough mass to counter the long drop proportionatly:
Http://cgi.ebay.com/aw-cgi/eBayISAPI.dll?ViewItem&
item=141914844
Another example of arts and crafts hanging lamp is the use of multiple chains for visual balance-again larger mass at the bottom helps balance these:
http://cgi.ebay.com/aw-cgi/eBayISAPI.dll?ViewItem&
item=144511022
Then there's always just overwhelming the eye with details on the bottom end and not worrying if there is a chain or rod:
http://cgi.ebay.com/aw-cgi/eBayISAPI.dll?ViewItem&
item=143617220 http://cgi.ebay.com/aw-cgi/eBayISAPI.dll?ViewItem&
item=144798772
You might look into antler chandeliers if you are doing a rustic look.
Have you thought of putting in a decorative beam part way across your room to break up the room visually and give your lamp some place to originate from lower down than the peak?
-Betty Cunningham (I hung a chandelier from a beam going across the room part way down my 18 foot A-frame-shaped bedroom ceiling)