I have had excellent experience with Delta - as a passenger, and when
transporting fuzzies.  You need to make reservations for them, and pay a
fee (mine was $60), and obtain a small underseat carrier.  You can have 2
per carrier.  There is a contingency (the number of animals allowed in the
cabin) so be sure they stipulate it in writing when you get your tickets,
and be there early.
 
You will be required to take them out of the carrier at the checkpoint, so
that the carrier can be x-rayed - be prepared to be mobbed - my fuzzies
loved it, then slept the whole trip.
 
Happy Skies .... Joanne and the Sugar Pops Posse
[Posted in FML issue 2433]