Paris neighborhoods - older woman traveling alone. Recommendations?

For useful recommendations, at a minimum you must include your budget window in euros.

If you are visiting the Louvre frequently, one assumes hotels along or near rue Richelieu to the north or in St Germain des Prés to the south might suit.

In addition to the above, you might also enjoy a stay on the Ile Saint-Louis. Although heavily touristed, at night, when the day trippers and tours are gone, it's very pleasant.

Safety is not an issue. As an old lady I wander around Paris day and night and use the metro as long as it is running -- sometimes with my husband but sometimes on my own. For convenience I would stay near the river in the 4th (Marais), 5th (Latin Quarter) or 6th (St. Germain). With the Louvre as an object the 6th is a good choice; it is also near the Orangerie and d'Orsay both of which are quite close to the Louvre. My favorite hotel for short stays is in the 5th and near the river for those evening walks around Notre Dame; the Cathedral illuminated at night is one of the wonders of the world, especially at the back. You will easily find a passerby who will take your picture with it in the background -- make a great holiday card next year. Our hotel is Henri IV Rive Gauche which is a small boutique hotel with views out onto an old church; small but nicely appointed rooms.

These 3 districts are convenient and charming.

I traveled solo to Paris as an older woman. I stayed in the 4th near the Hotel de Ville metro stop. It was convenient to walk to lots of sights including the Louvre, which was about a 25-30 min (for me) walk along the Seine and a really quick trip on the metro. I never felt unsafe anywhere in Paris and I too, like Janet, took the metro until late in the evening - had no issues walking to my apartment from the metro (about 3-4 blocks) as late as midnight by myself. I don't have any recommendations for hotels because I stayed in an apt.

Sounds like you just want something very convenient to walk to the Louvre and you aren't going to want to pound the pavement or take the Metro to/from other areas a whole lot. Since you don't give any indication of what price range you are working in, my best suggestion is to simply go on Google Street Maps, type in the Louvre to pinpoint its location and then click on the button "Nearby" to select "Hotels Nearby" and see what pops up in your price range in whatever you deem a "reasonable" walking distance. Then check out reviews on Booking.com for those hotels. You do not need to book your room through Booking.com, but I trust their reviews more than TripAdvisor because you cannot leave a review on Booking's site unless you have reserved (and fully paid for) a room at the hotel through Booking.com. While there, check the photos taken by travelers who stayed at the hotel - don't bother looking at all the professional photos from the hotel's website where everything looks much larger than it usually is.

As for accommodation, I'd recommend at that time of the year you opt for something with air conditioning just in case you find yourself visiting during a hot spell. Plus, if you aren't a city dweller in your regular life, you may appreciate the a/c will help drown out street noise or noise from adjoining hotel guests.

If you want to go for an apartment, check with Paris Perfect to see what they have in your budget. I've used them before when traveling with a friend, but wouldn't hesitate to use them next time I head to Paris on my own as they have a number of studio and 1 bedroom units, they are really accurate with their descriptions and photos of their units and they are extremely helpful, professional and really easy to work with - they can even arrange an airport pick-up/drop-off if you don't want to deal with taking the RER or standing in a long line for an airport taxi. They have an apartment on Place Dauphine which looks spectacular and that location would be awesome for anyone who plans to spend most of their time at the Louvre.