I think six years old is a great age! She will be settled into adulthood, but still have plenty of spunk left. She could easily live for another six or seven years. Maybe more.
I know you said she was already trained, but I always advise new owners to go through a training class with their dog. It is a great way to promote a strong bond, and is a lot of fun.
Good luck! And don't forget to post pictures!