We just got back from a Northbound one-way cruise on Princess. It was wonderful. You can add-on time a land tour of Denali National Park on either the Northbound or Southbound cruises (after the NB cruise, before the SB cruise). We were not able to do that due to time and cost, but I wish we could have. (If you can, definitely do it.)
Our NB cruise started in Vancouver, stopped at Ketchikan, Juneau, Skagway, and cruised through Glacier Bay (amazing) and College Fjord (equally amazing.) We disembarked in Whittier and transferred to Anchorage to fly home.
We read various opinions of whether Northbound or Southbound is better for a one-way cruise. We found that on a NB cruise the landscape gets more different/interesting the farther north you go, so every day was something new and exciting. We took a galley tour on one of our at-sea days. During it, they told us that they load all the food for the NB voyage, and the following SB voyage, in Vancouver... so I would guess that would mean that the food on the NB portion is fresher... although I had never seen that as a pro or con from anyone else. Just something to consider.