The "would prefer" part is okay. But if you say "the" class, it suggests there is only one on Friday. Unless she is the person who makes the schedule, I'm not sure what her preferences have to do with it.
She wants to fly to Dallas on Friday. She would prefer a flight in the morning. (One of several flights to Dallas that day.)
That's very kind of you to make me a birthday cake. If it's okay, I'd prefer [that] it be chocolate.
Student or Learner