With your land first, you will be very limited on your distance into Denali Park , unless you are sailing the very end of May into June. Mid May won't get you past the public road, with more and more opening every day. Dependent on weather and how much "repair" they have to do. Constant maintence.
I still recommend you get the Tundra Wilderness tour anyway, a priority for getting as far as you can into the park.
As for lodges, both stay in nice properties during the tour. Buses are very similar, with very comfortable seating. Rail cars, seats are assigned- I give an edge to RCI since Princess has table seating, with 2 riding backwards the entire way and their lodge out of Talkeetna is 50 miles away. RCI stays at the wonderful Talkeetna Alaska Lodge. Meals are extra unless specifically included, budget 50% more than you would at home for a cushion.
Bottom line on any cruise tour, do your homework. Go for as long as you can afford, avoid anything less than 6 days, too much time in transit. Factor in all transit times with your itinerary. Add at least an hour on each end for wait times, loading/unloading. Look for itineraries with 2 nights in locations, more time to do varied activites.
Be careful about Seward, Princess' Kenai Lodge is 40 miles away, and RCI rarely spends any time here. It's a gem not to be missed in my opinion.
Have a great time, interior Alaska is a whole another wonder.