One Night in Paris

The airports (CDG or ORY) are not close to downtown Paris so any hotel you choose will not have "easy" access to the airport. You'll either take the RER or a taxi.

lbenton,
It's not clear to me how your 15-hour layover occurs in relation to the "after 10pm" part of your question. There is an IBIS hotel at CDG that is unremarkable but will do the trick for a one-night stay. You could ditch your bags in their holding area, head to Paris, spend several hours, then head back to check in and crash at your hotel room.

However, if the 15 hours starts at 10PM, you could do the same thing for a few hours, but will need to head back around 2 or so in the morning to crash. Not as much time in the city, perhaps, but still probably worth the effort if you've never seen Paris. The city is lighted very nicely and -- away from places like the Eiffel Tower, Trocadero, and Notre Dame, can be quite beautiful and peaceful in the late evening. That said, I wouldn't hesitate to head to Trocadero (across the Seine from the Eiffel tower) -- it's kind of like an ongoing party scene with people from all over the world and terrific views of the illuminated Eiffel tower.

I should have been clearer: the layover occurs at night, so the 15 hours I have in Paris start at 10pm and include sleeping.

Thanks for the suggestions! I will look into the IBIS hotel near CDG.

What time is your outbound flight the second day, and where is it to (I.e. is it Trans-Atlantic?)?

Kim, we fly out at 10:40am to North Carolina, so definitely transatlantic. Would you stay closer to the city or the airport?

If you take the RER into Paris, that takes 45 minutes each way and the last one departs from Paris back to the airport around midnight. After that, night bus or taxi are your options.

You probably need to be in the airport by 8:00 a.m. at the latest for your trans-Atlantic flight, and 7:30 would be safer. The airport is huge and security can take just as long as anywhere else.

Much as I love Paris, I think that it could be very stressful to have this time pressure.

This makes sense, and I appreciate the honesty. I guess I was just excited about seeing Paris. Looks like I'll book a hotel near the airport, and we can consider taking the train depending on how quickly we get through customs and knowing we'd need to taxi back.

Any idea how much a taxi is from the Eiffel Tower to CDG?

It's a government-established flat rate of 55 euros, but fees can be added for advance booking, etc. I don't see that there's any late-night charge on top of that. This is one taxi company's run-down: https://www.g7.fr/en/paris-taxi-fares.

Do It! Even if you get to Paris close to midnight, you can get a taxi and follow Ricks's suggestion for a drive around the city to see the highlights. It's in his Paris book- just go to a library, borrow the book and copy his itinerary. He even suggests giving the map for the taxi driver to follow. Of course, you also have to go to the Eiffel Tower and see it all lit up. The Trocadero is a great viewing area. Also, walk a bit along the river Seine and across a couple of bridges. It may be a little costly to do all this by taxi but it'll be worth it. We've walked around the touristy parts at midnight and have felt safe. When you get back to your hotel, just make sure you arrange a wake up call and set a couple of alarms to make sure you wake up in time to get to the airport for your flight. Heck, you have all that flight time back to sleep so why not stay in Paris as late as you can, am I right?

Store your bags at the airport and power through the night. The City is beautifully lit although I can't remember how late the sights, cafes, bars, etc. stayed open. We were there for 5 nights in 2014 and one night I just went from major site to major site enjoying the lights.

Go For It!!! Go to Trocadero for viewing the Eiffel as it 'sparkles.' It 'sparkles' every hour on the hour after dark....which is pretty late in the summer. I believe it does so until at least midnight.
It will be a sight you will always remember. Don't miss it.

Thanks for the comments! I booked the IBIS hotel right next to the airport. We are planning on having as much fun in Paris as we can (definitely seeing the Eiffel Tower!) and taking a taxi to the hotel so we are where we need to be in the morning for our flight. :-)