CDG airport hotel vs Lyon

My instinct is to go with the plan for the train to Lyon on your arrival day. It’s not as though you are planning to drive in a jet-lagged state. It will save you an otherwise wasted day. The advice often given for getting over jet lag is not to sleep during the day, or to do no more than a brief nap. The ride would be an opportunity for that. Yes, there are trains from the airport to Lyon.

We've done both and I agree that taking the train to Lyon is the preferable option.
We slept at the airport because we wanted to go into Paris on arrival day to run a couple of errands before leaving Paris the next day. We got the errands accomplished but staying at the airport was a big yawn, kind of disappointing (except for us getting lost at the end of the metro line and wandering around a bit before finding our hotel).
Taking the train to Lyon was much more interesting and rewarding. My wife slept on the train. The best part is that you're already in Lyon that same day (rather than in some functional but boring airport hotel). And even better, you wake up in Lyon on your first full day in France.
There is a train station right at CDG. You can check https://www.seat61.com/ for good information on train travel.
Many posters here suggest 3 hours as a safe estimate for clearing customs and getting out of the airport, but that will vary according to a number of factors beyond your control (is your flight on time? Is the airport particularly crowded?, etc).
There are hotels right at the airport so no shuttle would be needed. We stayed at the Hilton at CDG.

Absolutely do not spend the night at CDG. I will note that when we went to the CDG rail station for our train to Strasbourg, there happened to be a security alert (abandoned luggage, I think) and we were kept out of the station for over 45 minutes. This raised the prospect of having to throw our prepaid, discounted tickets with seat reservations into the garbage, and buy a walk-up ticket (no doubt in a long line at a window.) However, they re-opened the station in time for our train. Just keep regular travel issues in mind. This year, that includes labor actions! Think about your last day as well. Many people don't allow the right travel time to get into the long check-in line for Economy air tickets.

You should familiarize yourself with the SNCF website. The drop-down box entries will give you a idea of which trains pass through which stations. That will pay off if there are any disruptions in your travel. (Not trying to scare you, just talking about being an informed traveler.) Have you considered taking the TGV right to, say, Avignon? Or do you have a real desire to see Lyon? If you're worried about sleeping past your stop, you could always set your phone (SIM card or not) alarm. I personally stay up as long as I can on my arrival day, but you will be learning what's best for you.

Such great information from all of you; thank you! My preference would be Lyon over the airport, so will go with that. Our original thought was that Lyon would be a shorter trip than Avignon. I was not attached to Lyon except as a place to rest up.
So now a different question: we planned on 2 nights in Lyon then training to Avignon and picking up a car there and then out to regions of Provence. In our plans we were only going to do a quick day trip to Avignon from our base near Arles. Would just going straight on to Avignon for 2 nights at the beginning instead of Lyon be a better plan? (A friend noted yesterday that we might be sorry to miss a stay in Avignon!)
We will for sure avoid the airport hotel and I appreciate the advice. And the info about the time it could take in the airport and the train schedule info was also good.
Thanks to all!

In response to your most recent question, and as a former resident of Lyon and a recent visitor to Avignon, I would like to offer that Lyon is far, far more interesting than Avignon.

Provence is fine. And Avignon is OK. But Lyon has much more to offer. In general, I would err on spending more time in Lyon rather than more time in Avignon.

My two cents.

Julie, Lyon or Avignon? I really think this is personal preference. We took the train to Avignon from CDG and spent 2 nights there. We had a pleasant day sightseeing, at a leisurely pace. I think you should read up about both destinations and decide which one appeals to you more.

Lyon beats the pants off of Avignon (and Lyon is closer). But, Avignon is a poor choice as a base especially for someone with a car. Or did you just mean to spend one night to get over jet lag?

BTW many people find jet lag to be partially manageable through diet etc., you might want to try some of those remedies out this trip.

Great info all! Settled: Lyon it is! We will visit Avignon on a day trip. We will train to Avignon when we leave Lyon and pick up a car at the Avignon train station.
I appreciate all of the responses. I’m sure I’ll have more questions as I go along.
And in addition to your responses I’ve read lots about avoiding jet lag. Hope it all works! I spent my first 2 nights in Italy in Rome and it’s a blur. (But I was so excited I never slept on the plane!) I’ll be much more prepared this time!

Great info all! Settled: Lyon it is! We will visit Avignon on a day trip. We will train to Avignon when we leave Lyon and pick up a car at the Avignon train station.
I appreciate all of the responses. I’m sure I’ll have more questions as I go along.
And in addition to your responses I’ve read lots about avoiding jet lag. Hope it all works! I spent my first 2 nights in Italy in Rome and it’s a blur. (But I was so excited I never slept on the plane!) I’ll be much more prepared this time!

You've made good decisions. But I'm prejudiced because I dislike Avignon but love Lyon; and hate the idea of staying at an airport hotel.
As to jet lag, I always get over it after the first night in France. Coming home is a different story. I'm now on my second full day back from France, and still suffering.

The TGV arrives at the gare Dieux, which is is about half a mile from the first river. We walked it in 20 minutes or so, but there also cheap trams and a small subway system - depending on where your hotel is. I wouldn't take a taxi.

This is a bit off topic, but we took the TGV first class from Paris to Lyon, and had a laptop sitting on the table of a four way seat system, and one of the guys opposite of us apparently grabbed the computer while we talking and ripped it if off. The thieves don't look like low-lifes - they look like normal people. So never let your guard down. If you get on the TGV and put luggage in a luggage rack near the door, I would bring a cable lock and lock it to something so someone doesn't make an early departure with your luggage.

And I would vote for Avignon over Lyon.

Lyon is more of a big city but as distinctive. It does have good restaurants if you can find them in Vieux Lyon. You end up walking long distances, and the architecture is not particularly distinctive. Its a little bit "blah"

Avignon has an older core with real city walls, and the medieval streets and the pope's palace with a view of the Rhone. Its a smaller place and more walkable. There are more tiny cozy shops, and there are some very nice restaurants there as well.

However, when you arrive by at the Avignon TGV station, you need to take a local train 10 minutes to central station, and from there, you just walk out the door, and you are at the city walls, and 15 minutes from the pope's palace.