Need recommendations for a place to rest in Paris after a long flight

You know your husband better than we do, of course, but conventional wisdom is that a nap is the worst thing to do with jetlag - it just makes it worse.

The best thing to beat it is sunshine, gentle walking, staying outside, staying awake.

I don't know if this would work for you, but perhaps consider a lounge pass to use before you exit the arrivals hall? You would follow the connections signs, not exit signs so you don't exit the secure area. Air France has a business class lounge with lounge chairs, showers. There are other lounge options which may offer more.

He always insists on a short nap after a long flight. But then he goes outdoors and stays awake until at least 9 pm local time.

How about a hotel at CDG with a day or hourly rate?

There's a new Yotel opening at CDG on Nov. 14th if that fits your trip schedule. See Yotel.com

If it's raining, you will be out of luck with the park bench scenario. He can't sleep in a cafe or restaurant, or the employees will have to ask him to leave. Sleeping in churches is disrespectful, IMO.
Here's a website advertising rooms by the hour or afternoon, in all neighborhoods in Paris:
https://fr.roomforday.com/en/hotel/france/ile-de-france/paris.html

What about a (very) quick nap on the way from the airport to the Airbnb (if traveling on a taxi or metro)? I would try to sleep as much as possible on the flight itself. Then once on the ground, just fortify yourself with some strong coffee and take advantage of the sunlight. I fight off sleeping until bedtime unless I am literally falling apart.

If it were me, and I didn't want to pay for a hotel, I think I'd try finding a quiet corner of the airport to zone out. Earplugs and eyemask. Once I got out of the airport, I'd be too stressed to nap.

My question: Is this your first time that you're traveling abroad? Generally upon arrival you get a burst of energy and then later in the afternoon the groggyness sets in. I normally set up a very active day and then it's lights out near 9 or 10. Sometimes I'll book a Paris walk so that it forces me to get out and go. Your biggest goal is to get your bags to your AirBnB, after that the sky's the limit. I suggest to never waste your arrival day.

But just taking a nap after arrival, I think most people here aren't going to suggest that.

Assuming your flight arrives on time at CDG around 9AM, figure it will take you about an hour to get through the line to have your passport stamped to enter and pick up your suitcase (unless you are flying carry-on only). If you are taking a taxi to get into the center of Paris, you are probably looking at another 40 mins (depending on traffic), so it will be close to 11AM. We traveled to Paris this past June and our flight also landed at 9AM and it took us until 11AM to get dropped off in front our our rental in the Marais. If your husband can't make it the 6 hours until your 5PM check-in, you have a couple options to mull over...

First, look into the airport business class lounges to see if you can get a day pass there.

Second, check with your Airbnb host to see if the apartment is open the night before. If it is, pay for the extra unused night with the understanding you expect the host to let you in early once you arrive the next morning. The owner of the apartment we booked offered that option, but we chose to drop off our suitcases and wait until 4PM to check in. Having slept 2 hours on the plane, we were tired, but had a long lunch, sat in a cafe for a drink, took a walk, did some window shopping, scoped out the grocery, wine shop and bakery near our apartment to purchase stuff to get us through the first night and have breakfast foods, snacks and beverages in the apartment. By the time we did that, it was 4PM.

Third, look into booking a bed (or beds) in a nearby hostel with a liberal check-in policy - some may let you check in whenever you get there, others might have a noon check-in, others later still. Find one that will fit your schedule but make sure they don't have a lock-out in the middle of the day to clean (a few hostels still do this and don't want guests in the rooms during specific daytime hours for cleaning). I've stayed in hostels where I've been able to check-in as early as 10AM. Depending on the number of beds in the dorm room, you can typically have a bed for 20 to 35 Euro per person. If your husband can sleep on a hard park bench in the middle of the day in the center of Paris with sirens and traffic noise, even a twin bed in a 4, 6 or 8 person dorm seems like a giant step up in comfort and quiet as most guests are off doing their thing during the day. Many hostels also offer private rooms for 1 or 2 people, but expect to pay around 60 to 75 Euro for those. Hardly worth it if all he wants is a comfortable place to lay down and doze off for a few hours on his own - might be worth it if you are also wanting a place to nap, or you want to take a shower and use the common area lounges and WiFi while he is resting. Check hostelworld.com to read reviews, see photos, amenities, etc. but reach out to the hostel directly via phone or email to inquire about the earliest you can check-in and make sure there is no mid-day lock-out. Book with the hostel directly on their website if everything checks out.

Even though we fly from the Midwest to Paris, or some other French city, we always plan our arrival schedule to be able to get our rental car, drive for a short distance (or cab it in Paris), and then check into the hotel if possible. We usually try not to drive for longer than two hours plus.

Hopefully, we are able to check into our hotel, take a nap, shower and then go out for lunch or to do a bit of sightseeing. If the hotel is not ready, we may have lunch and then go back for our nap and shower. We will have a fairly early dinner and go to bed around 9:00 or 10:00p.m.

I know this flies in the face of conventional RS and other poster's advice but this has worked for us. Plus, even though we constantly tell ourselves that we will be all packed and ready to go at a certain time, there are always last minute things to do. From where we live, we have to drive at least an hour to three hours to get to the chosen airport. We have to deal with our car parking, check in with the airline and go to the gate area after spending time in line for TSA checks. All of this already makes me tired so I am tired as I start my trip.

So, we will see if our "drive, hotel, nap, shower, go outside, eat" plan works as well for us for when we arrive in Marseille in two weeks!

I like Ceidleh's suggestion.

If napping works for your husband then that is what he should do. I fly from a small airport with limited flights in the Pacific Time Zone. When I left in August I had to get up at 3:30 PDT to catch the 5:15 out, arriving in Paris at 8:30 the next day. I nap or sleep if I need to and I'm usually fine the next day. I do have plenty of time so spending a few hours attending to what my body needs is my priority on my arrival afternoon.

If the day is nice there are plenty of those cool green chairs in parks that the Parisians seem to nap in.

Thank you all for your suggestions. Suspect he will nap in the airport after we arrive. I never sleep in airports so can keep an eye on our luggage.