Many travelers from here pack a small roll of duct (gaffer's) tape, and a flashlight.
The Chief is right about that flashlight-I got a little LED keychain light at a dollar store and use it
1) when in the upper bunk [no windows there, so it gets really dark], and
2) to check under the seats for anything that has rolled/been pushed there during the trip.
There are nightlights in the roomettes, but those roomettes are small enough that the lights inevitably disturb the other person in the room.
Re: backpacks.
I have traveled thousands of miles this past year with only a largish soft backpack, a size that easily fits in the overhead compartment on an airplane. The pack has several pockets and compartments, enough to carry a laptop, chargers, shoes, winter wear. When it is not full, it fits under the roomette seat. I do have to take out some items to squash it down enough to slide it under the seat. Depending on what exact sleeping car you have, you may have a small, tall closet, one barely wide enough to hang two coats. It will have some room on the floor to stash some items from the pack. Or, you may have no closet, and instead a larger arm rest along a wall that has a place where you can hang your coats on hangars (which are provided). There is a belt attachment to hold a taller pack or piece of luggage upright below the coats. I have had both types of roomettes on the Eagle, but had the no-closet variety earlier this month.
Here is the secret, though, for using the backpack. Store everything in large plastic zipper bags. For example, your toothbrush, toothpaste, comb, lotion, etc, whatever you'll take to the restroom in the morning, that's all in one bag. Computer- and phone- cases and chargers in another. And specifically, a full change of clothing goes into a single bag. So your nightwear is in a bag. In another bag is the next day's entire outfit, including socks and underwear.
I get gallon or 1.25 gallon zip-lock bags at the grocer or dollar store, and have new, clean bags for each trip. I assemble the contents of each bag and fold the clothing sufficiently to slide the pieces into the bag. Then I sit on the bag to press out any extra air; this also flattens the clothing without causing bad wrinkles. Finally, I zip the plastic bag shut while it is completely compressed. The package looks almost as if it's been freeze-dried.
For things I can't sit on, I suck out the extra air with a plastic straw while I'm zipping the bag shut. Doing this really minimizes the space needed for everything that goes into the backpack, and helps organize the backpack. Once I am in the roomette, I can take out the plastic bags with my nightwear and the next day's outfit, snuggy them into one of the nooks and crannies in the roomette, put my toiletries on the armrest or tray table, and squash my now thinner backpack under the seat. The plastic baggie keeps the next change of clothing together in one place [an important consideration in the confines of a roomette]
and clean, in case I spill my coffee or juice.
Re: that roomette closet that I mentioned might, or might not, be there. Others talk about using duct-tape to deal with temperature control and vents. In my experience with those closets, they tend to rattle in the night, and a little of the tape [or a flip-flop, pushed under the door] can make for a better night of sleep. Those flip-flops, by the way, are mighty handy for use when you go to the shower on the lower level of the cars.
Enjoy your trip - it will be
great.