The Tilt/Shifts are becasue I have never used one, and always wanted to. Also, I assume any cruise around Alaska would allow some land excursions, which is when I would like to take a the 24 TSE to get some super sharp landscapes with DOF from your nose to forever. The 17mm TSE is because the 24mm may not be wide enough for the grandness of Alaska.
The 24mm f/1.4L II is for night shots of the stars. The f/1.4 plus a high ISO camera should allow for great shots with a fairly short shutter speed (see some of Jonathans recent shot http://www.huyerperspectives.com/Lan...ta#!/i-8VZpDQK ), but maybe not a short enough shutter speed for a moving boat. As for the DOF, with a FF camera and focused at the hyperfocal distance of 44.6', the DOF at f/1.4 is from 22.3' to infinity. That alows me to get a pretty good foreground and a nice star filled sky in sharp focus. Works for me.
If you want some easy time laps shots... get a GoPro with different stick-on mounts. Stick a mount on the side of the boat where no one will see it and let it start taking pictures or movies. It sets up easy, it takes decent pictures, it comes with a water proof housing, you can set it up and walk away, and it is cheap. Here is my first attempt at a time laps: http://www.flickr.com/photos/60479608@N05/9338641160/
Pat