I have a family of inexperienced flyers, none of which speak English. A direct flight from South America is $800 more than a 1 stop alternative, but we are afraid of them being overwhelmed or lost during a US connection. Choices are DFW, ATL or EWR (Newark?)

Are any of those three choices substantially simpler? Note, they are two grandparents flying with their 6 year old grandchild. All are on a tourism visa to visit their son (and me) at Christmas. We live in Boston. I'm inclined to skip Newark for weather reasons, but would do it if it's easier than the others.

Thank you in advance for your guidance.

You said they are coming from South America so I assume they speak Spanish. Of the airports you named I think they will find the most Spanish speakers at DFW. Any airport can be overwhelming to an inexperienced traveler but at DFW there will be more people who can offer help in Spanish.

Which language(s) do they speak? None of those are overly easy but there is a lot of help for some language groups.

Just be sure to not book any short connections in case they need extra help through immigrations, etc.

oops -- I missed the South America bit.

If Spanish speaking SA -- they will have no problems at all.

There will be spanish speakers at all three -- but ESPECIALLY at DFW.

Newark is one of my least favorite airports, I'd pick one of the others. I would also make sure that the flights are on the same airline and the same ticket, and allow plenty of time for the connection as they will have to clear passport control, collect their bags (right outside passport control), clear customs and drop off the bags.

Not only Spanish speakers but I believe a lot of the most important signage at DFW and ATL is in Spanish as well.

Atlanta is a confusing mess, IME, don't know about DFW.
One other consideration, especially with a young child, is total flight time. As tiring as travel can be, a few hours more or less can make a real difference in the comfort (or misery) of the trip. The length of layovers too make a difference.

Of course you would not want to do it, but if necessary, someone could drive from Boston down to Newark to pick them up.

Strange as experiences differ. I found Atlanta super easy.
Newark too.

I wonder if if makes a difference if you are arriving on a domestic flight or an international flight. My experience with international flights has been only from East Coast airports.

Atlanta is certainly not a confusing mess. It's as easy as A, B, C ... well, make that easy as T, A, B, C, D, E, F. Everything is in a line and there's a train between them all.

It is true about Atlanta that everything is in a line with a train in between. Maybe I was just super tired by time I got there.

So, honestly, the opinions of WoinParis and NoFlyZone are likely accurate and more trustworthy than mine.

The assumption of more Spanish speakers at DFW reflects some bias not, IME, borne out in current reality. I hear more Spanish at EWR! Plus, signage is pretty much multilingual, especially at EWR as it is a United fortress hub and they have broad South American network.

Of the choices, I'd go with EWR. And if you are really worried, the $2400 you'll save will more than cover you to go to EWR to meet them. Can even take the train.

I use DFW frequently and it is very easy to navigate.

Of those I've only used Atlanta, but it was super easy, nothing especially confusing one way or the other.

We found the directions for the train at DFW very confusing the first time .

My vote is to meet them at Newark. Either drive your own vehicle (with boosterseat) or take the train to EWR.

From what country? Are you sure those are the only choices?

EG Copa uses Panama City, Avianca uses San Salvador.

Many other SA routes go via Miami or Fort Lauderdale.

IF their visa makes them "eligible" to use the APC kiosk, you may want to warn your grandparents that they will need to interact with this machine upon arrival. It understands several languages, including Spanish, but can be a bit confusing.
https://www.cbp.gov/travel/us-citizens/apc

I'm going to do a spit-take if the family is from Brazil after all this surmising about Spanish speakers.

DFW is THE major AA hub. All international arrivals (regardless of if they are on AA) are into Terminal D, which is the newest and nicest of the terminals. Catching the Skylink tram that is WITHIN security is easier from terminal D than from basically any other terminal. American also has domestic flights that originate at D but the Boston flights are likely out of A or C. There are numerous maps that will help detail which tram to ride. The trams run in a loop, so if they choose the "wrong" direction, they will just get to their disembarkation point a little later. ATL is linear, and that means that if they miss their stop, they just have to backtrack.

EWR during Xmas time is a bloody mess, as is the whole NY-DC flight corridor, which includes seven major airports in NYC, Philly, Baltimore and DC. A flight to Boston from Atlanta or DFW will transit over and around most of that congestion bc Boston is the only major airport north and east of NYC.