Hello LisaB, and welcome to cruise-chat;
I just came from the Princess website and there were cabins available in almost every catagory (except E, FF, GG and HH) so I guess I'm not clear on why you could only get an obstructed view. If you want some other catagory cabin you or your travel agent should be able to book it now.
I also wanted to check out your cruise, as this is one I had not heard of. It looks terrific--lots of sea days, which I love. I've been to Australia and New Zealand, but not the particular area you are going. Any cruise has the possibility of rough seas but they are usually very smooth. It is nothing you can control anyway, like the weather, so I wouldn't worry about it.
I would like to hear more about your cabin situation, so please keep in touch.