PL
There is so much to consider seeing and experiencing in Paris. Big museums, little museums, particular houses, walking tours, the big tourist sights, wandering through neighborhoods, cooking classes, churches, music, bakeries, dining experiences, walking or boating along the Seine, parks, flea markets, galleries and street vendors. And more … antique shops, haute couture, book shops, cemeteries (yes, that’s a thing for many) and still more.
Look at guide books and not just Rick Steves’. The Michelin Guides for Paris and for France will serve you well. Others include DK Eyewitness (great for photos and neighborhood walks), Moon and Lonely Planet. If you speak French, Guide Routard. The RS website will lead you to many podcasts and TV shows. https://www.ricksteves.com/europe/france
Figure out what sings to you. But I suggest you spend some real time in Paris, being there and not day tripping. And you can also spend other time in one or two other places. (LATE NOTE 9 nights; 8 full days. Two places other than Paris is pushing it, unless one or both of the two is/are just done a day trip; travel days to/from Europe really don’t count and travel days within France cost two to six hours of “being there.”)
Our first trip to Paris (2010) was for a week. 6 full days, 7 nights. We never made it outside of Paris; no day trips to Versailles or Giverney, though both were on our minds. There is much to see and do and experience in Paris. (Our first trip to France skipped Paris altogether; we spent a week in Provence)
Our second trip (2023) was intended to be four nights in Paris and three days with a day trip to Giverney. We spent two nights in Chartres and one night in Versailles on our way in to Paris, so we had slower visits to those sights and cities and not as day trips from Paris. We ended up with an extra afternoon and night in Paris courtesy of British Airlines (BA). In Paris, we mostly saw different stuff. The only intended repeat was the Luxembourg Gardens. The one unintended repeat, due to BA cancelling our flight, was a repeat visit to Musée de l’Orangerie.
We are now planning a third mini-stay in Paris at the end of a larger 30-day trip and I have asked others on this forum to chime in with suggestions. See https://community.ricksteves.com/travel-forum/france/paris-suggestions-s-il-vous-plait
Follow your heart and Bon voyage.