Have I got idea's ?? You bet.
I assume you will be wanting a piece of the Inside passage to to start you must look at where you want to leave from. 7 Dayer's..... I can only recommend leaving from Vancouver. We left from Seattle this summer and you miss a lot. You need to decide which ports you want to see also as some lines do not go to Skagway and the White Pass& Yukon RailRoad I think is a must see if you are only going to do Ak once.
Bellingham of course is just a hop and a skip from the border so I'm sure your rellies there will have lots of idea's about seeing the countryside around here.
We travel about the Lowermainland of BC and Upper Washington State quite a bit also so when you get down to something specific give me a shout. We have an Alaska /PacNwest forum here also with info you might want to start checking. Check the link above under "Port Information"
and of course the least expensive way to see the real coast is via the Alaska State Ferry system that leaves from Bellingham anyways..
(Fairhaven) Bring your tent and put it up on deck.