We did this trip last June and loved the Coral. We used the ship's shore tours and were more than satisfied. A must is the heli ride to the glaciers, as well as a Mushers Camp. Loved Denali but found the transport on the trains, buses, etc to be very crowded and hectic. ( maybe it is just me, but I get tired of being herded around) Lodges are lovely.
Have a wonderful trip and do everything you can. Treat the trip like you will never return and never have another opportunity. Remember, when traveling,we only regret what did not do, not what we did!