What cell phones and service providers are there that do well in rural
areas?  I live and travel in rural Kentucky.  The best I've been able
to find is a Mitsubishi T200 with Cellular One but need something
better.  One compatible with the chargers and external antenna I have
for the T200 would be great, but good reception in weak signal areas
is most important.

Cell phones in rural areas are always a problem and coverage depends
mostly on how much the service provider is prepared to spend on the
rural network (which usually ins't much) so the service is usually
poor.  The only difference between handsets is the mode.  CDMA is the
best.  The inards of the phones are all much the same and the specs
likewise don't vary much.

You could ask the service providers for a coverage map of the area
that interests you.