OK, I found a good suggestion in another thread re: getting to Whittier. If boat leaves at 8:30, what time would you recommend getting there to board? I'm sure it takes time.
"Best solution: use a bus or a train to get to and from Whittier. There's two train departures from downtown Anchorage, the first being a regularly scheduled train departing at 9:45 a.m., arriving at 12:05 p.m., with tickets sold by the Alaska Railroad; the second being a train chartered by Holland America Line departing at 12:45 p.m., arriving at 3:35 p.m., with tickets sold by Holland America Line. There's a bus departure from downtown Anchorage departing at 3:00 p.m., arriving at 4:45 p.m., operated as the "Park Connection" with tickets sold by Alaska Tour & Travel. There's a bus departure from downtown Anchorage at 1:00 p.m., from the Anchorage airport departing at 2:00 p.m., arriving at 3:45 p.m., operating as, with tickets sold by, "Alaska Cruise Transportation."