I went to a TA with using Princess in mind. The one place my wife wanted to go while doing the interior of ALaska was also dropping into Canada to see the Yukon and Dawson City. \
The TA may have been giving us a "line" maybe not, but the brochures she showed us noted that HAL went into the Yukon while Princess didn't (at least in last years brochures) so I went with HAL. We saw numerours busses with "Princess" all over them in Denali and the train Stations (Alaska RR) but after that none,,at least on the roads we took.
Princess, HAL, RCI and Celeb all offer cruise/land tours in Alaska. They are all good. Just recommend doing the land tour portion first (because its intensive), then end with the cruise for a bit more of a relaxed pace.
Wth any cruise tour purchase- DO YOUR HOMEWORK. There is plenty you may not realize that is not disclosed in the brochures.
Key points- meals are not included, budget 50% more than you do at home for a cushion.
Be aware of distances, my recommendation is you need AT LEAST a 7 day add on. any shorter has too much time in transit, never consider the 3-4 day options, all day on a bus, not time at the destination. BE well aware of the DIFFERENCES in Denali Park "tours" Princess mostly now only includes the worthless Natural History tour. If you want to travel at least 6 hours by bus or 8-10 hours by train for only a VERY small portion of the park- a 3 hour tour, then fine, going in only 17 miles. But you have missed the superior Denali Park options. The Tundra Wilderness tour goes to mile 53, but there are also 1/3 cost SHUTTLE buses, taking you up to 85 miles. It's interesting that a lot of brochures include the "famous" photo of McKinley reflected in Wonder Lake, when NONE of the cruise tours include this and few have any time for it.
My clear preference is to fly into Dawson City. The endless bus ride over only a lot of so so scenery is not my preference. Again research the areas fully the more you know the better. The include Kluane is mostly a waste of time, you have no opportunity to get to the scenic highlights with HAL.
For a reference- the train Whittier -Denali Park is 10 hours, bus about 7 with stops. Realize that the McKinley Princess and the Denali Princess are 100 miles apart, way too many people think they have another option to tour the National park- none. The nearest town from the McKinley Princess is 50 miles away- Talkeetna, very few activies at the lodge and McKinley viewing even rarer. So plan the shuttle carefully and make the most of your time.
There is the independent option, allowing you the freedom to see and do what is of interest for you. With a toursaver, it is significantly cheaper and superior.
Meal options---When I took my HAL cruisetour there was an optional meal plan which I would stay away from if you are so inclined to sign up for it. The parent company of HAL owns Westmark hotels which is where you stay mostly on a cruisetour (didn't in McKinley or in Anchorage) and what they don't tell you with the mealplans is all your meals have to be at their restaurants in their hotels (the meals on the McKinley explorer were paid for too). Most of the people on our tours that took it were sadly disappointed. If you don't want to get up early for a full breakfast,,you wasted your money. Suprisingly the hotel restaurant in Tok was really good, the restaurant in Whitehorse was really bad. Those people were stuck there. I forget what it averaged out to be but I do recall a lady claiming that she basically spent 25 bucks for a cinnamon roll breakfast one morning. I think their worst was Dawson City. So many places to dine there but they were stuck at the Westmark,,,,really nice motel,,so-so food.
Dawson City,,we left Tok on a bus,headed north to Eagle (got to visit Chicken , Alaska, now there is something to behold) where we toured, then after lunch took a boat down the Yukon river to Dawson City. It was a long day, but not all on a bus.
The only real advantage of a cruisetour is you don't have to think,,everything is where it has to be when you need it. As Karen pointed out, you move at their pace not yours. Am I glad I did it,,yes for my first time in Alaska. Next time,,I will do it on my own.