Jenny,
I am a Princess girl, and cruised Alaska twice with them.
My favorite included Glacier Bay. I did prefer that to Tracey Arm.
Both called on Juneau, Skagway & Ketchikan. All awesome places, with tons to see & do.
To be honest no problems at all with rough seas with Alaska cruising.
For cabin location, this is one you want to have a balcony for. It is worth every penny!
Mid ship is good. They rotate the ship when cruising the bays, so to be honest not much of a difference being port or starboard.
Good Luck with your choice & have a great cruise