Where to stay with 80+ year Mom - Her first trip

Have you considered Île Saint Louis? It's a bit quieter than some central areas (e.g. the Latin Quarter). The Left Bank, the Right Bank, and Île de la Cité are all very easy to access from there.

The only downside is that it would be at least a couple of blocks from a métro station, depending where on the island you are.

Beyond that, I would look for a place very close to a métro station with an elevator or escalator. This site lists the most accessible métro stations (with wheelchairs in mind, but it would still be helpful info in your case, I think): https://www.parisinsidersguide.com/accessible-metro-stations.html

I am in my 60s with an injured knee (so I feel your mother's knee) and just returned from my second trip to Paris this year and have been who knows how many times over the years. Do not be fooled by the existence of an escalator or an elevator at a station into thinking that the metro is a good idea if your parents absolutely need to use one. Elevators and escalators break or they are in spots that require a long walk up and down stairs to reach them. I'll give an example of a station that I know pretty well: Bastille station. It will show up as a station with escalators but one is for the upward bound 8 line which is 6 to 8 stories under ground at Bastille and the escalator takes you a set of stairs for the final two to stories. Another escalator takes you up the equivalent one flight of stairs after you gave gone up and down the equivalent of about 4 flights of stairs to get to it. And not to mention that the escalator on Line 8 was not working for about three days last week. I know that because I took the 8 from Bastille to the 2nd arrondissement and when I saw the out of service upward escalator, I took two buses back. I would suggest that you look for a place to stay on a good bus line; personally, I like Lines 86, 87, 69. Stay in Saint Germain or the Latin Quarter near bus line 86 or 87 (basically near Blvd Saint Germain). Bus 86, 87, and 69 take you to the Bastille market and 86 takes you to Marche Aligre/Marche Beauvau if you are interested in great food markets. When you look for an apartment if that is the way that you go, if you need an escalator, ask questions about how reliable it is and if it goes to the floor of the apartment. I stay in an apartment where you need to go up about 8 steps to get to the elevator and it stops one floor below the apartment. Frankly, after the elevator went out last month, I now advise people who need elevators to stay only in places with at least two. Why do you think that an apartment is a better option for your mother to rest?

I'm afraid that you're incredibly late to try to find an apartment for this September. People book up the good apartments a year in advance.

If I were you, I'd concentrate on securing two rooms at a centrally located hotel. The Ile St. Louis isn't a bad option.

I know you didn't ask about your itinerary, BUT I feel the need to speak up on behalf of your 84yoa mother WHO HAS A BAD KNEE. This is WAY too much walking for a 5-night trip. Out of the gate, I would drop Champs-Elysees and Versailles. If you want a day trip outside the city, take her to Monet's home and garden in Giverny, which will be stunning in mid-September. It's a small garden compared to the Tuileries and easily navigated. A visit to the Orangerie to see the finished product makes a nice pairing with Giverny (though probably not on the same day).
I cannot imagine that she would want to climb the Eiffel Tower, let alone stand in line for the torment of doing so. You'll see the ET from your seine cruise and, likely, other outings. A nice way to see it lit up at night is to have dinner aboard Bustronome (https://bustronome.com). It's a splurge, but the food is surprisingly good. And it starts at the Arc de Triomphe, rolls slowly down the Champs-Elysees, and passes lots of famous landmarks. She would have to navigate the stairs getting on and off the bus.

I just realized that you mean this September. That could be tough but if you have a big budget anything is possible. Are you aware of the current issues around vacation rentals in Paris? Also, consider an aparthotel. That could get you two bedrooms but it may have to be outside of Saint Germain or the Latin Quarter. I put my brother-in-law and sister-in-law in La Clef Louvre for a gift trip and they loved having the kitchen and the central location and a person at the front desk for ask for help/directions. I don't think thatLa Clef has two bedroom suites but it is part of the the company that owns Citadines which has other properties in Paris that do; I think those are their Bastille location and the one near Trocadero but generally I have found that two bedroom suites are pretty hard to find at Parisian aparthotels.

Speaking from the vantage point of 85 with a bad knee, for the river cruise I would suggest looking into the Bateau Bus. It is a rather basic cruise operation but they have nine stops along the river from the Eiffel Tower to the Jardin des Plantes and and your ticket is good for 24 hours of hop on hop off riding and it can be extended to 48 hours for a very small amount. We like it because there is so much to see along the Seine that it doesn't get tiresome and when we get tired of walking and need a rest we just say, "Let's take a boat ride." Have a great ttrip.

I am close to your mother's age. The following comments are based on our experiences, June 2025. For Giverny, you can take a self-guided tour with air-conditioned bus for your transportation. If you want to go up the Eiffel Tower, book dinner or lunch at one of the two restaurants (pricey) but I believe they have their own dedicated elevators. Forget the metro - use taxis and have cash to pay them to avoid any credit card hassles. The lines to get into Notre Dame look long but they move fast - we only stood in line about ten minutes. For a hotel, see if the Citadines in Saint Germaine is available. We have not stayed at that one but the Citadines we used in London had two bedroom suites and a full kitchen. If you want more details, send me a PM.

There are Seine cruises that don't require steep stairs. In fact, there is only one that does, the Vedettes de Pont Neuf. I'd avoid this one.

The Bateaux Parisiens are located on the Right Bank side of the Seine near the Pont de l'Alma. It has a gentle incline down to the boats.

The Bateaux Mouches are located on the Left Bank side of the Seine in front of the Eiffel Tower. There are steps but they're not steep at all, and have hand rails.

As Cynthia suggested, the Citadines in Saint Germain is in an ideal location, or look for an apartment on Ile St Louis. This is our favourite place to stay, and although I've never caught a bus, I believe that one of the good bus lines crosses the island which would be perfect.

Citadines definitely has lifts, although I'm not sure about two bedrooms. I only stayed there once a long time ago and that was in a studio.

If your budget can run to it, do lunch at Jules Verne. We've been three times and it is perfect. Lunch is half the price of dinner and personally I prefer the daytime views anyway. We went for an anniversary dinner once, and the taxi drove us right to where we were met and escorted to the private lift. It isn't far and all flat, there is not a single step and the views are stupendous.