We sailed the Crown this past August and are going again on Feb 16th. Its a beautiful ship. I cannot speak firsthand about Balcony rooms, we typically get two inside cabins or oceanview to save money. For the amount of time spent in the cabin, we personally don't feel its worth the extra money. However, I would like to go the extra mile and get a mini suite some time, this primarily because the bathrooms are large and they have tubs.
The demographics on all the Princess cruises we have sailed were varied. I think you'll find a wide variety. Being a couple, I would advise hanging at the adult only pools. That's also a great way to meet other couples. Good luck