Couldn't say it better - the drive is well worth it if you've got the chance. Dad and I did it back in 1989, and I did it again in 2015. Been getting itchy to take three months off again and go for a drive, so possibly another trip in a couple years.
The best time in Skagway was about 15 minutes after the cruise ships blasted the horns. Everybody went scampering back to the ship except the locals and a handful of us that drove in, leaving it a nice peaceful place at night. I'd photograph the few final rail moves for the day and then go have a few brews at Skagway Brewing. Pretty good beer if you get up that way. Just don't ring the bell.