We took the classes before we had my DD: childbirth prep, baby care, breastfeeding, etc. because I felt like any information would be helpful. Far and away, the best (and most useful) class was the breastfeeding class. It was a three-hour class led by a lactation consultant. My DH hated the childbirth prep class and honestly, it was probably the least useful of all of them, but still, I am glad we did it for the experience.
Also, make sure to get scheduled for a hospital tour where you will be delivering.