Hi annet2011, welcome to Cruise-Chat! Since you'll be in an interior forward or aft really won't make much difference. You'll want to be close to the elevators, but not right there as you can get noise from others not as courteous as they should be. I think you would enjoy the Caribe deck. The Plaza has some public areas, so there may be more noise.
I hope you enjoy Princess as much as we do, they're our favorite line, so far. The ships are immaculate, the service is impeccable, and the food is wonderful. I have heard rave reviews about Alaska, just too cold for me
Have a marvelous cruise!