Mitch, I have taken the Alaska ferry and what you read is true about pets. They are not allowed upstairs and have to remain in the vehicle. But at the time the ferry stops to load and unload vehicles etc. at various ports along the way, you can access you pets and if they happen to be in port for a while, you can leave the ferry and walk around on "dry land". But boy, you had better be back when they are ready to leave or else... Beth can tell you more about that though.
As to sleeping accomodations. When I was on board with my friends we booked a stateroom for the two nights we were to be on board. But as was mentione, you can sleep in the lounge, but have to be up and out with your stuff by 8. You can also sleep in what is called the Solarium on the upper deck. They have lounge chairs up there to spread out in. A number of people did that too while we were on board.
The Alaska Marine Highway starts taking reservations on December 1st of the year prior to your leaving. Like yout go in June of this year, you can make reservations anytime now. If you call them they will send you all the necessary papers. They charge by lenght of vehicle. The sooner you get the reservation papers back to them, with the dates you want to go, the sooner you will be acted upon. Now I am not sure if maybe you can make the reservations over the phone or not. We sent ours in the fall before we were ready to leave and were among the first to be notified in December.
Truth be told. It is a wonderful experience taking the ferry up the Inside Passage. They travel in areas where the big cruise ships can not go. You really see a side of Alaksa that the cruise ships can't. You meet some interesting people from all over the world cause there aren't as many people on board as the cruise ships carry. You get to talk with native Alaskans and find out a lot about places to se eand things to do and just about life in AK in general. The ferries are sailing 24/7 so you can stop at a port in the middle of the night as well as daylight. And with 24 hours of daylight in mid summer, it only gets twilight dary for a few hours. The scenery is so fantastic that you spend all your time on deck. We hardly used our stateroom, except for some sleeping when we got tired. I would do that trip in a heartbeat again.
Here's a link to their site
http://www.dot.state.ak.us/amhs/