We have nursery nurses on my postpartum unit. None of my hospital's four postpartum floors do couplet care. That is only done when we are extremely short staffed. I've been working there for almost 2 years and never experienced couplet care. You can either be a Mother and Baby nurse or soley a Nursery nurse. I do both as I see it as a benefit to know how to care for adults and newborns. That means when I get to work, I may be listed to work in the nursery and the next shift I may be listed to work on the floor.
Since you will be a new grad, I would encourage you to apply to a postpartum unit and be open to learning both, because you never know what can happen. My floor has experienced new grads who absolutely love the nursery and end up being stuck soley in the nursery and hardly ever working on the floor as a Mother nurse. The rare times they were on the floor, they were lost. They were struggling on knowing how to hang antibiotics, give BP meds, etc. That's terrible if you're a new grad.
If you would like to take care of very sick babies (i.e. NICU), the Mother/Baby unit is a good start. A few of the new grads on my unit finished up their 1 year have now transferred to the Neonatal Unit and are NICU nurses.