I would like to hear from anyone who has done the Bellingham ferry. I have a dear friend in Bellingham, so this would be a perfect trip for me.
I've looked into this as I live in Seattle. It would be a neat experience but it's SO expensive. For example, a 3 leg trip Bellingham to Sitka to Whittier costs $814 per person one way and that's if you take a tent and sleep on the deck and bring your own food. Adding a cabin adds 100's of dollars.
For comparison, you can get a 7 night RT cruise out of Seattle with really nice room with daily service, sail by glaciers, activities, and all the food you want cooked for you!