Hi again! Hope you are getting excited about your trip on Friday.
A bit more Amtrak seat info. As mentioned, when you board, either a car attendant will help you pick a seat, or you can choose any empty seat yourself. But before taking a seat, look to see if there is a little paper tag, called a "seat check" hanging from the luggage rack above the seat. See the picture below. Note that in this picture, there is only one tag on the 57 Window side. This means the window seat is taken but the aisle seat is available. Either the color code or a written station name (3 letters) will tell the conductor or car attendant where you should get off, so they can make sure you are awake and ready.
If you want to switch seats, *generally* you can, just pack up your stuff and move to another seat without a tag, and it is okay to move your tag yourself. Every now and then you'll run into a conductor or car attendant that tries to keep pairs of seats available for couples or families boarding. If they don't want you sitting there, they'll ask you to move back or find another single seat. They shouldn't get annoyed with you as long as you cooperate and move back.
It is a bit more of an issue if you move to a seat in another car. Often car attendants will group passengers getting off at a certain stop in one car, so they don't have to wake people in multiple cars. Also, they may know that a large group is boarding at a station ahead, so keep a group of rows open for them. So don't assume that because there are a bunch of empty seats in another car that you can grab one. It never hurts to ask nicely, though, especially if your car is too cold, too hot, or has some noisy people.
And as also mentioned, you can hang in the SSL lounge *almost* as much as you want. If the car is full it is polite to leave for a few hours. If not full, you can look less like a lounge lizard by not taking too much stuff with you. A small bag with your id/wallet/phone/knitting supplies is fine. Your main luggage over your seat will be perfectly safe. In all my years of travel I've never encountered a luggage thief, they have better things to do than ride trains. Another way to avoid being a lounge lizard is to occasionally move from a table to a sideways facing seat, so that people enjoying a snack can use the tables.
p.s. In another post, we can discuss the loose relationship between your train's scheduled departure and arrival times and any known version of reality...