Lurker mom here, but I wanted to suggest being at the appointment after the 20 week ultrasound/anatomy scan. If there is a concern about your baby, they may not tell you at the ultrasound itself, but rather wait until the first appointment after it. (Some places are not allowed to tell you anything, and therefore leave it for your doctor to discuss with you. Those appointments may also be scheduled back-to-back, so this may be a moot point.)
Also, any appointment she seems nervous/worried about would be good, but you probably already figured that out. Other than that, the guys nailed all the important ones.