I've visited two of the four parks that make up this World Heritage Site, with two separate visits to Glacier Bay National Park and two separate visits to Wrangell-St. Elias National Park. I absolutely love this site and I'll admit to some bias: while staying overnight at the Kennecott Lodge in Wrangell-St. Elias, overlooking the Root Glacier, my now-wife and I decided the view was so perfect that this was the time and place where we should get engaged. So this is a World Heritage Site that will forever be part of my own personal story.

There are only two roads into the National Park, but unlike some of the more remote parks in Alaska and Canada, it is reachable from more populated areas. The 59 mile, unpaved McCarthy Road, an old mining road which offers spectacular scenery as one progresses into the interior of the park, starts at the town of Chitina (which is a 4 hour, 45 minute drive from Anchorage along easily traversable paved roads). Be warned that there are a lot of nails and railroad spikes along this road, and the morning after we got there, we discovered we had a flat tire. The lodge staff was able to arrange for a fix during the day while we were out hiking. In our stay there, we explored the abandoned Kennecott Mine (with its distinctive red mill building being the largest wooden structure in North America) and hiked to (and on) Root Glacier. Getting to the interior of the park is doable by driving, but definitely take precautions and take care -- but it's worth doing and is an unforgettable experience. Though the road is just 59 miles, you'll need to drive slowly (and you'll want to make lots of stops for the scenery anyway) -- expect it to take around 3 hours.
We separately visited Hubbard Glacier, which is not reachable from the interior of the park. It's one of the rare North American glaciers that is expanding. We took a small boat out to see it and it was truly breathtaking. Wrangell-St. Elias is the largest National Park in the United States, so even seeing two areas in separate visits, we only saw a small amount of what this park offers. As mentioned, there's another road leading into the interior of the park (a different section entirely than where the McCarthy Road leads), and many people do scenic flyovers of the park. There's a lot to see and do here and everything is absolutely beautiful.
At Glacier Bay National Park, we got views of Lamplugh Glacier, Margerie Glacier, Johns Hopkins Glacier, and Reid Glacier. I worry for a future where people can't see these magnificent things. While I know the world is always changing and the landscape will still be beautiful when these are gone, the glaciers up close offer a vivid, electric shade of blue that I once never thought I would see in nature.