My husband, two grade school aged sons and I went on a 14 day cruise with Volendam leaving on January 2, 2011 from Sydney. This was our second cruise. Our first was 14 months ago, and was a ~12 day cruise from Barcelona on a Royal Caribbean ship that we enjoyed greatly.
We had booked our flights ourselves, and had spent one night in a local hotel that we had found. A friend who had moved to Sydney from the US picked us up at our hotel, and after he gave us a lovely tour of Sydney, dropped us off at the ship. Check in was a snap.
Our sons had one interior room and my husband and I had a second interior room adjacent to theirs. It was clean and tidy, and the room steward and his assistant were both excellent. In general, though, when you book interior rooms, I think there's not a lot of variation between ships.