Merril,
I thought that I would not be able to cruise them on the Concierge level, so we did Penthouse for the Istanbul/Athens cruise. It's comparable to a regular suite on RSSC. The Concierge cabins, after seeing them, are comparable to the cabins on the PG - totally tolerable for such port intensive sailings. If there were more than one or two sea days, a Penthouse would be a definite requirement for me. Amenities, except for butler, are the same. We're doing concierge level for the Baltics since I don't expect to be in our room all that much.