Paris from May 13 to June 8

Lol I know. And that’s the problem how to organize the days . I am more used to the “if it’s Tuesday, this must be Belgium “. type of holiday. We are staying in the 4th arrondissement. Close to lots of sights. I’m wondering if I should just plan for a day to Versailles and maybe to Reims and just wing it for the rest of the trip? Or have a more structured itinerary for each day or every second day?

Too much thinking needed. Hahaha

What you'd want to think about ahead of time is whether you'll be taking any day-trips that involved TGVs, the fast trains whose ticket prices range from bargain-basement if you buy really early to possibly painfully expensive if you buy much later. That can make the difference as to whether a day-trip is affordable or not. Unfortunately, the cheap tickets are not refundable; I think they are now changeable for a fee plus whatever the additional cost of current tickets (but I have not verified this). With the coronavirus situation we have at the moment, I can't recommend that anyone buy non-refundable train tickets, but YMMV.

I do not set up day-by-day sightseeing plans. I have a list of things I want to see that shows the days and hours each sight will be open. I make up a little chart showing each day of the week and the unusual things going on that day--what is open late? what is closed? what is free (to be avoided or not)? With that cheat sheet I can see at a glance what my options are on any given day, and I can make a decision based on the weather and what I feel like doing.

We are planning our own month long trip to paris in September. We ave ben before and have a few simple tips for anyone going for an extended period. First, plan one major activity a day such as The Catacombs, The Louvre, Musee D'orsay, Eiffel Tower, etc. (Reserve a timed ticket at the official website for these busy places and avoid the up-charges you find on third party apps.) If one major attraction a day feels right, spend the rest of the day wandering the streets and visiting shops and cafes. If you are feeling especially energetic you can always add in public parks and spaces like the Tuilliries, Luxembourg Gardens, Sacre Couer or Arc De Triomphe that are easier to see without a reservation.
Don't miss the Musee Carnavalet - a museum about the history of the city of Paris. I tell friends to start with this amazing museum. Understanding the history of the city will enrich your everyday experience int he City of Light. Don't miss an evening visit to the Jardins Du Trocadero to see the Tower light show at sunset. Of course with an extended stay, day trips to Giverney and Versailles are a must. Check out the schedule at Versailles for the evening light shows and make sure you venture around the grounds to the Trianon palaces and L'hameau, the faux village built for Marie Antoinette so she could play house as a milk maiden.
If an overnight is possible, a few days in the Loire River Valley top see the chateaus is well worth the trip.

I'm more apt to sent up a tentative plan for each day even over a long visit. I travel solo and I don't want to have to think of what I want to do every day at breakfast. I want to have a goal. I DO also want to have the ability to swap out what I thought was going to be a "garden" day for a museum or church day if the weather is not wonderful.

Things I would consider:

• Will you be getting one or more museum passes? With your time available I'd probably plan to visit the Louvre several times as well as d'Orsay at least twice but you might not be as crazy about museums as I am. Those admissions might be museum pass or for the Louvre I'd probably just go ahead and ticket thru the official Louvre website. Anyway, I'd stack your museum visits for pass days then do churches or non-museum pass sights in between when you use the passes. With the amount of time you can avoid the Monday/Tuesday closure problem pretty effectively.

• Are there any special exhibitions you want to see such as the Atelier des Lumieres? I'd work the special exhibitions around the Museum Pass days. https://www.atelier-lumieres.com/en/node/1064 Many love this venue and it's presentations. I saw the Van Gogh one here last Fall and was not as blown away as others still, it's something you might enjoy.

• Are there English language tours on certain days at museums? At the Musee du Luxembourg there is a special English tour given the 1st Saturday of the month if you are interested in the current exhibition on Man Ray. BTW, if this artist interests you, you can also see his grave in the Montparnasse Cemetery.

• The last couple of visits I planned out a walking tour for myself based on sights taken from guide books, from forum posts and from Corey Frye's online walks.

• Are there any Paris Walks that you want to do? Some are standard and given every week while others rotate thru the month. I'd slot in the non-weekly ones first if there are some that are of interest.

• I'd do day trips on non Museum Pass days except for the ones that are covered by the pass such as Versailles, Chantilly, Malmaison. Day trips not needing a Museum Pass would be something like Chartres.

• Anything odd that you'd like to see from the Atlas Obscura Paris pages?

Yes, so many possibilities - I'd start with a list of what looks good to you and then slot them in on days that would work. I'm not big on down time so I'd be happy to do museums and churches every day, lol! Well, with a few cemeteries thrown in! Beautiful time of year to be in Paris!

For a trip of this length where you can afford to be quite flexible, I like acraven's suggested approach. I would make a list of categories of things you want to see/do and place them in categories with all the relevant logistic information (e.g. museums, outdoor spaces/parks, historic sites, day-trips, shopping/stores, outdoor markets, cocktail bars, etc). I also second the suggestion to research if the day trips can be done with local regional transportation whose price never changes, or are TGV-type destinations.

Unfortunately, the cheap tickets are not refundable; I think they are
now changeable for a fee plus whatever the additional cost of current
tickets (but I have not verified this).

In a very rare change for these days, the current policy simplified in May 2019 actually generally made things more flexible. The vast majority of TGV second-class tickets (aside from Ouigo), even cheap advance-purchase tickets bought many months in advance, now have the following policy:

Billet échangeable (ajustement au tarif en vigueur) et remboursable
uniquement avant départ : 5 € de frais dès 30 jours avant départ, puis
15 € 2 jours avant départ. Dès 30 min avant départ, billet échangeable
2 fois max (même jour, même trajet) et non remboursable après 1
échange.

In English:

Ticket is exchangeable (fare differences will apply) and refundable
only before departure: €5 fee starting from 30 days prior to
departure, then €15 fee starting 2 days prior to departure. Starting
from 30 minutes prior to departure, the ticket can be exchanged a
maximum of 2 times (for the same day and the same journey) and is not
refundable after 1 exchange.

Ouigo trains have their own much more restrictive policy, but in my experience the vast majority of "normal" TGV tickets now have this policy (I check on oui.sncf where the policies are stated very clearly for each ticket).

Thank you all so much for the great info. Some of the ideas for places suggested to go see , I hadn’t even heard of! I was also thinking that a tentative itinerary for each day would work best. My only real stumbling block right now is the Coronavirus! I hate to book and pay for entrances to sights and then maybe have to cancel, and not get a refund. I still plan on going unless something drastic happens.

All good advice above. Listing the places you want to see and specific things you want to do, tentatively slotting them into days that make the most sense (like reducing crowding), building in some totally unstructured days, getting any TGV tickets as early as possible (new exchange policy is very helpful), etc. Stay flexible enough to adapt your activities to the weather. Look at no more than one "big" activity each day, usually best in the morning so you can take the time you want and then base the rest of the day on your energy level.

You'll have time for lots of day trips -- Versailles, Chartres, Reims, St-Denis, Giverny, others. Depending on where you're staying and what your budget is, you might consider a few overnighters to places like Bayeux or one of the Loire towns, where a one-day trip doesn't leave enough time to really enjoy. So you're paying twice for the same night -- it's not the worst thing you could do!

Paris Walks is a good outfit, whether their regularly repeating walks or the special ones they offer. And leave plenty of time for strolling, cafes, parks, laundromats and such.

I'd wait to book sights for now as well. You've got 2 months before your travel so I'd probably start evaluating that a month or so out. I WOULD make a list of things you'll want to ticket ahead. I don't ever go up in the Eiffel Tower but if that's on your list, I'd probably go ahead and book that 60 days out.

I'd not be booking much that is non refundable now since it is unlikely the Corona epidemic will be reliably over by then.

Don't forget to consider the weather in your plans. We spent about two hours in the Louvre on a beautiful day two Aprils ago. Bailed after a coffee break to stroll the Tuileries.

Lucky you! Have you picked up RSs Paris guide? You can download an electronic version from his app. I would focus on his self-guided walks so you can see everything.