by law ANY airline HAS to provie acess to serivce dogs, otherwise its descrimination, least in the usa (other countries have different ruls on SD acess laws.)
that being asi, make sure shes wearing her SD vest (even if it says in training, and call to confirm a few times with the airline before your flight make sure theres a note put on the manefest that you will be bringing your service dog with you onto the flight. the laws for public acess are the same all over the US so you shoudlnt have any acess problems from state to state in terms of legality, however i would, if possible print out a few copies of the service dog laws from the ADA website or any other site with SD acess info, just in case.
unfortunatly MOST people (security, airline attendants ect as well as places in your home town (ie stores)) are NOT familiar with the rules (or that fact that there are service dogs other than labs...) so having a copy of the pamhlet just adds as extra backup if your ever given any issues.
its preferd that the dog stay on the floor by most airlines so i do suggest taking a blanket or pad with a familar scent for her to lay on and if possible ask for a BULK HEAD seat (this will give you more leg room, meaning more room for her to lay down comfortably at your feet if the flight is busy.
and of course, make sure to have a copy of her rabies cert and if possible have your vet just give you a letter stating shes up to date on shots and healthy...
good luck.
(and if you dont mind me asking, what kind of services is she training for?, it always interests me to see what other service dogs are training to do)