Planning a cruise to alaska, solo, inside passage from Seattle, which is best RCCL, or Princess, Rhapsody, is a little older than golden princess or star princess.
Absolutely the best advice I can give somebody planning a cruise to Alaska and asking basic questions like this is: find a good local Travel Agent who is a CLIA Accredited Cruise Counselor (look for the agent's diploma on the wall, not just an agency sticker). Ask your friends and co-workers for a recommendation. The service is entirely free to you. ACC's are trained to find the very best cruise for you, after learning your personal situation and preferences, and work hard to get you the very best rate.
There are so many ins and outs to an Alaskan cruise that you need expert advice. For example if you want the newest ships, they seldom do the Seattle itineraries. You may find the newest ships on the North-South itineraries. A Travel Agent can give you all the details.