Bobbi, when we were on Rhapsody in 2000, our balcony stateroom had robes.However, we found out from our tablemates (in an ocean-view cabin) no robes. They were on their honeymoon, so I ended up loaning her my silk one that I had drycleaned for the trip. :-)
I would think, though, that you could perhaps ask the cabin steward for one, but that would be a crap shoot if you got one.
Yes Princess has bathrobes for use, however, you may have to ask for them as we did. Our cabin steward placed them on our bed the first night in our balcony cabin AB cat, then they disappeared the last night of the cruise, this was on the Ocean Princess Feb. 2002. Going on the Golden in a mini suite Dec. 14 2002.