We chose our room to keep control over room size, having a veranda, what deck the room is on, as well as the position of the room on the ship. That said, the ship we were on felt very stable and I expect we would have been fine anywhere.
Also FWIW we did a different route (starting and ending in Vancouver) but they all look great!
I would see if you can reserve a dinner time and look at excursions quickly as they do close out.
Hope you enjoy! Sounds wonderful!