For clairfication- Mighty great trips is NOT the helicopter operator and only a booking agent, and no this is not a good option. You want to cobook this with Orca Enterprises and Coastal Helicopters. Key here is saving an hour in shuttle time, since each drops off for each other. They are in the same area- over 10 miles from downtown. If you book separately- you will be on a bus twice going back and forth downtown.
As for the Skagway Streetcar- I am sorry to see the orginal vehicles gone- they were the charm. They have all been replaced by modern- "buses" . They do offer an excellent commentary with top notch guides. A great choice if of interest. But have you also considered getting into the Yukon? A highpoint for most, with a car rental. There is an excellent mile guide- South Klondike Highway log www.explorenorth.com
Hiking is great, consider the Lower Dewey trail of just walking back to the Gold Rush Cemetery. Most important consider the free Park Service walking tours, all different depending on the ranger and just excellent. http://www.nps.gov/klgo/schedule.htm
Lois is probably the top operator in Ketchikan, book her early!!!!
I have gone with both Orca Enterprises and Coastal many times, with Larry 4 times this year. So yes in my opinion, great choices.