We were in Ketchikan on 7/3/07...our best excursion was the Rainforest Canopy Expedition! It was $165/ea for 3-1/2 hrs. We were taken by bus (from the dock) & then 10-min later transferred to a large 4-wheeler (looked like a converted hummer), which took us up to a lodge in the mountains. After being outfitted with the harness/cable rigs & safety instructions, we each tried out the zip-lines on a short practice line---and then 7 long zip-lines + 3 rope bridges followed! It was incredible!
We are mid-50's & didn't find it strenuous at all.
(Ketchikan's zip-lines was much better than the seat zip-line we saw at Icy Strait Point---which was one zip-line sitting in a seat/$85).