Last cruise we were in with the Star Princess, we took the 8 hours bus ride into Yukon, and the driver dropped us off the downtown (just one main street) and we did our major shopping there. I found it to be cheaper to make purchases in Skagway than other ports. Also, we had taken a lot of pictures in the downtown area. There is no need to a cab or bus ride, as it is very close to the terminal.
If you're a beer drinker try the Alaskan Amber. Brewed in Juneu. Mighty tasty! Have some at the Red Onion Saloon, an old saloon (and former brothel) from the gold rush days right on the main drag in Skagway.
We took the Yukon horseback that left at 8am and had plenty of time to visit around Skagway when we returned. I know Southeast has done up to 3 tours a day if there is a demand.
The tour was great as we stopped and glassed for wildlife and spotted wild sheep on the mountain. The guides were helpful and shared some fun time in the cookhouse at the end of the tour.
Emeald lake is out of this world and shouldn't be missed.
Our friends rented a car and drove to the camp and spent some time in Carcross on their return to Skagway.