I am a many time Alaska visitor, but I never recommend any one way cruise without at least 5 additional days touring. It is a long way in time and money not to take advantage of it. You will see very little allowing only a couple days. Distances are vast and a highpoint is of course Denali Park. As for tours- look over any ship shore excursion list and narrow down your interests. Budget for costly tours and consider at least 1 flight. Each area offers great "walking tours" easy to go on your own and far more enjoyable than some costly tours. I never book anything from the ship and always book direct from the operators. I agree that with a full boat from Orca it would be uncomfortable- but I wouldn't choose Allen Marine based on their snacks.
As for sightings - the comparism is invalid as it isn't known what the other saw on the SAME day. For your air- keep looking and see what is around- this way you'll know when a good deal comes along. Don't forget if you fly to Seattle (where I always go) you have a transfer that will be around $100 for 2 people. Add also 3+ hours.