Here's some of my tips/, sorry if that have already been mentioned.
-Bring snacks! The cafe car can be expensive for four people, and the dining car meals are currently not good. So bring PLENTY of snacks. They cannot store it for you though, so keep thatin mind.
-I would strongly advise you bring a power strip. If you are not in a bedroom you will only have ONE outlet. If you bring a power strip you will be able to charge multiple devices at once.
-Much of the trip (especially around New Mexico I would think) there is NO service. So bring books, coloring, etc. Anything that will keep you busy when you cannot use your devices. I personally though, would be looking out the window as the scenery through New Mexico is really pleasant.
-With four people, I'd advise you to not spend much time in your rooms. Spend time in the sightseer lounge car. It is located towards the middle of the train, behind the diner and in front of the coaches. There are floor to ceiling windows, lounge chairs facing the window, and plenty of spaces to charge your device. It makes a great place to hang and meet other people. In the downstairs there is a cafe, however the prices are on the steep side, so maybe don't purchase from there. Oh, and cashless purchases only from there in the pandemic.
-Tipping your dining staff and sleeper attendant is the norm. Be prepared. I, being young, don't know exactly how much, but I'm sure other can advise you on what to be prepared for.
-I see you already booked. But seeing the age of your children, I would definitely opt for the roomettes or bedroom for any future trips. The family room may be a bit cramped with four people. And I'm sure your (then) teen would enjoy the extra space/privacy that comes with the bedroom/roomette.
-Masks ARE required at all times in the train, unless you are actively eating or drinking. Not sure your thoughts on that, but keep it in mind. According to (very) recent updates, you should have your mask on in your room, however I doubt it will be enforced. Just close the curtain.
-Take advantage of the shower! It's honestly not that bad to use. And I'm sure with four people you will want to use it. I'd advise you to use it at a fresh air stop for the first time as they are longer and will give you a chance to get use to it without being bumped around.
-The train can get very late. Expect a delay of up to 90 minutes. Now, BNSF (the company who owns the tracks) are generally good with the Chief. However it has been seen running over 5 hours late.
-With Amtrak staff, it's a hit or miss. There are stories of terrible crews who couldn't care less about your experience, and others that will make it one you will always remember.
-Don't try to bring all your luggage in your room. Just down the hall from you will be large luggage racks that should have no problem accommodating your luggage. Put all/most of your bags there when you board, find out your room, then get situated. Maybe pack to ensure one bag has all the necessities in it, so you don't have to rummage through it all. Any luggage that you check can NOT be accessed under any circumstances.
-Don't get off at any station that is not a fresh air stop. if you do, do not stray more than 10 feet as they will leave you.
-The last thing I can think of, is just be open minded and respectful. In the end, this is public transit. Just enjoy the ride.
Also, I should be hopping on the Chief on the 27h from Fullerton (first stop outside of LAX) to Chicago. Would've been fun if we were going at the same time...
If I think of anything else and remember this post, I will be sure to tell ya!
Oh, if any of you are into history, between Raton and Lamy (I think) there are many semaphore signals on the line. This is the ONLY line with these that receive regular service, and are going to be replaced soon. And you will pass the final wig wag that services a 'main line' in Delhi, CO. And of course, this route is FULL of history. You can probably easily check Wikapedia and see some of it. Happy travels.
So sorry this went on forever...