I’ve only taken the short train ride to Whittier from Portage, but Mom and her sister took this, and I’ve driven everywhere by road, except the dirt road to the north slope.
The trip south of Anchorage to Seward may be even more scenic, along the Turnagain Arm especially, but it’s driveable, as the road parallels the train, mostly.
The outside viewing platform is indeed super nice, and allows photographing without having to shoot through windows.
Great adventures I always recommend are fllying from Talkeetna to Mt. Denali above the Ruth glacier for about 50 miles, flanked by mountains on both sides, and maybe landing on the glacier. Ruth glacier looks like a giant, 1-mile wide, white freeway with many crevasses below us.
The pilot cranks down the skis by hand after leaving the runway in Talkeetna to land on the glacier.
Flying around the mountain in addition is also amazing, which hardly anyone does. Few realize this shows the highest, unobstructed vertical drop in the world; though, at an angle, because Denali doesn’t have foothills, like Mt. Everest, etc.. I’ve only done that once.
Another amazing adventure is the 26 Glacier Tour out of Whittier, south of Anchorage. Pristine and highly recommended!