Tipping is voluntary, optional and a highly debatable subject on AU.
Many of us give the SCA $10 per day per person. This can increase if (s)he goes beyond normal, or decrease if less then normal. If you say never see your SCA at all during your trip, it may even decrease to $-0-!
For the Dining Car, this is much more debatable. Some give set amount. (Like $2-3 for breakfast, $3-4 for lunch and $5 for dinner.) Some give 15-20% of the menu price. Some gone nothing.
KmH tips pretty much the way I do, except I am a tad more generous in the dining car, $3-4 for lunch, $5 for dinner. I agree that the situation of the dining car servers, with union wages and good benefits, is different from waitstaff in a regular restaurant, so don't tip 15-20% that I do "landside" but do tip.
Remember, you are on the train with the dining car staff for awhile, and trust me, they do remember.
I'll echo what most people have already said. It can't be emphasized enough that Amtrak employees are paid very well and have full benefits. If you don't tip a waiter in a restaurant, or your cabin steward on a cruise ship you are basically robbing them of their income (like it or not.. that's how the system is set up). So if you choose not to tip based on the quality of service, don't feel guilty.
For the Dining Car, I will tip, as others have already mentioned, $2 or $3 for Breakfast, $3-$5 for Lunch, and $4-5 for dinner. If it's a multi-day trip and the service is bad for multiple meals, I'll usually stop tipping altogether. As others have said, the staff remembers who tips and who doesn't and tipping every meal will usually result in slightly better service (if it was great service to begin with, than continuing to reward that service also makes sense for me).
The Sleeping Car Attendants I've started to tip less and less. I've tipped anything from $0 - $40 per trip. I've gotten pretty tired of SCA's being pretty bossy and telling passengers at what hour they can and can't have their beds put down etc. I also feel on a multi-day trip I should be offered additional bottled waters.. I shouldn't have to ask for them. Basically I've started tipping the "I'm just going to do the basics of my job" SCA's less and save that cash up for the really excellent SCA's that actually care.
So if I go on the Sunset or Zephyr and have a 2 night journey, but the attendant only does the basics of his job... I'll give him $5-$10.
If I go one night on the City of New Orleans and have an excellent attendant... they may get $20.
On my recently completed EB journey, my good SCA received $10/night.
For the Dining Car wait staff, if the service meets my expectations, I will estimate what my meal would cost and tip 18%-20% of my estimated total. On both evenings, my table mates and I were still talking and enjoying ourselves when the Dining Car was closed or about to close. We received a "message" from the LSA one night and the waitress the next night that "it was time for us to move on" (and stated in so many words, of course.) The tip I left each night for dinner was in the range of 10%-12% and made note of this unfriendly guest experience to Amtrak with names, train number, and dates.
For the SSL Cafe Attendant, I always leave a $1 tip.
As others have said, on my past Amtrak trips, the Dining Car staff do seem to remember who does or does not offer a gratuity and I have noticed a difference in the friendliness of service. Not so on this trip on the EB.
I tip my SCA $5 per meal delivered to my room and/or $10 a night if they provide self-service ice. I'm not sure I agree with the $10 per person guideline. According to that rule a two child family traveling for two nights would be tipping $80 to an SCA that performs fewer tasks for fewer customers than hotel staff that would be lucky to be paid half as much. The dining car is where 90% of my disappointment comes from, so these days I tend to avoid it.
The dining car staff don't really bother me directly but the way they bark at other passengers who make simple mistakes and boss around new customers who don't know the ropes really grates on my nerves. If the food was really good I'd probably still visit in the same way the Soup Nazi was popular on Seinfeld, but the honest truth is that I've had friendlier service at McDonalds and fresher meals at Denny's. There was a time I really wanted the dining car to get better but now I wonder if it's just permanently broken and maybe it would be better to have a discount on sleeper fares like on the Silver Star.
In some cases the on board staff are still willing to go above and beyond for their customers but are being squeezed out of tips as Amtrak removes or restricts a growing number of helpful tasks and services and little niceties the staff previously performed. I'm not sure what to do about that. On the one hand I'm sure it sucks for the staff but I don't really think it's the customers' responsibility to keep tipping for services no longer rendered.
My tipping for the SCA depends totally on what service I received. This summer we had one SCA who helped me with even my carry on bag, brought water around frequently, asked when we would like our bed made down and had the room looking great when we got back from Breakfast. He kept the bathrooms clean, the shower stocked, though he did ask that if any passenger saw a mess to please let him know. He was generally in the car except during meal time when he was getting meals for others. He would stop by to say Hi asking what he could do to make the trip more enjoyable. He I tipped $50 for both of us. He also took everyone's bags to the door downstairs when getting off.
In the Dining Car, the server who remember our preferences, made suggestions, smiled, and generally took good care of us, she got a lot more than my normal ( $2,$3, $5.)
Yes, the Amtrak staff receives a good hourly wage, but gratuity is known to be a part of what they will earn when they are hired. Giving a SCA a big tip, I hope is rewarding and incentive to continue the good work. The MIA SCA gets a zero tip and a letter to Amtrak. The good SCA also gets a praise letter to Amtrak. Many of these Amtrak employees take pride in their work, making passengers happy, and are long term in their positions. This trip I met two SCA's who had 15 years on the same train as an SCA. They always smiled, dressed smartly, and were there for the passengers.
I think the $10/night/person guideline is probably too generous a guideline.
Here's why: a couple years ago I took a trip with my wife from Virginia to California in a bedroom. Her cousin hopped on in coach in Chicago, and hung out with us in the room during the day. Our SCA kept our ice bucket filled. Arriving in Martinez, I palmed him a $50 because I thought it was a fair tip for the service provided. He started to chase me down the platform, thinking I'd mistakenly given him too much.
This wasn't some green SCA who couldn't care less. He was an old-time professional.
So, if $50 is enough to cause the SCA to try to give you a refund....
And it's a two night trip from Chicago to California...
And lets forget about the cousin....
For about the best level of service I've experienced on Amtrak
$50 / two night / two people = $12.50 per person per night is over-tipping to the point I was chased down the platform.
So, the HIGH end of tipping is something less than that. What's the low end?
As the other poster notes, and Amtrak explicitly states, tips are not required but are appreciated for good service. If you receive good service, by all means recognize it with a tip. If you don't or can't afford it, don't succumb to this notion that you're going to insult anybody by your tip or lack thereof. Chances are you're never going to see your SCA ever again - so who cares if they are insulted. And if they ARE insulted, whose fault is that? It certainly isn't yours or mine. But even for minimal service if the can is kept reasonably clean I'll throw $5 - $10 TOTAL just because that means they are keeping everybody else's crap (literally) from ruining my day. I'll go higher if I cause a problem (like the time i tracked in a TON of rock salt into my room from a wintery, icy Milwaukee platform).
I will note what I think is an important exception to this, and thats when tipping is really just a flat out bribe. The first meal in the diner and the first drink from the bar I will always tip on the heavy side, because it DOES result in better service. And tip for your ice - especially tip for your ice when you get it yourself. Nobody gets credit for giving you this free ice, but you can get credit and goodwill by tipping for it.