Welcome to the New Cruisers, PEM, mirren05, and regensburger, and hello to the venerable penny3333; I will second all of penny's remarks. My longest cruise to date (18 days) was on Sea Princess and it is one of my most memorable; Ft. Lauderdale to L.A. through the Panama Canal. I thought I might get a little bored but it was a great mix of interesting ports and long, luxurious days at sea. As penny points out, Sea Princess is smaller than the Grand Class ships, but that can be a good thing. She may not have all the bells and whistles but she is a very COMFORTABLE ship; very relaxed and easy to get around, but still with all the amenities we have come to expect from Princess. The Verdi pizza restaurant has the best pizza I've ever had--PERIOD!
I love the big ships too; but I'll always have a warm place in my heart for Sea Princess.
regensburger, I'm a little confused by your post as Sea Princess seems to be in the Caribbean in March '07, not Australia. But in any event, as to packing, you don't need to bring a robe--just ask your steward for one when you board. And for dinner you can get by nicely with a dark jacket, and two pair of trousers, one dark and one light.