We will arrive in Paris late April for 5 day stay. What specific attractions, ie Louvre, etc would need tickets purchased prior to our trip? Thanks
With places limiting people because of covid, I would make a list of where you want to go and check each website. I always do this anyway before a trip to check closing times/days, price, any closures due to renovations, etc.
I only know from a pre-COVID trip to Paris. We bought museum passes and splurged to have them delivered to our hotel. That ended up being a good idea and saved a lot of time. We also got online tickets to the Eiffel Tower with the elevator ride. We skipped the line and it was a beautiful day. While it worked for us, the next day was cold and windy and the Eiffel Tower was closed. If we'd chosen that day, we'd have been out of luck. Paris was the last stop on our 3-week trip and we were tired. Tired physically but more tired mentally from trying to figure out things in French. (Sadly, I have no French.) It's a big town. Following a friend's advice, we bought two-day tickets to the Hop-on, Hop-off bus which included the river boat. Granted, it wasn't the most time-efficient but it got us to the major attractions in an informative, less-stressful, out-of-the-weather way and we covered a lot of ground. It's not something I would have done at the start of a trip when I have more energy but it was a good way to end. This worked for us.
I would suggest you watch the ticketing sight for the Louvre. I looked at it this AM and there was still plenty of availability for entry tomorrow so you may not need to book real far in advance. Right now the furthest out they are booking is March 31. Last Fall there were some dates that were booking out so that's why I'd suggest watching how the ticketing times are going. You'll be after the Easter holiday crowd, I suspect, so things might be back to a lower level of visitation so good to watch.
**Editing to add - well since this AM they've added the availability to purchase Louvre tickets out thru the end of May, so start keeping a watch now for the particular day you are interested in.
https://www.ticketlouvre.fr/louvre/b2c/index.cfm/calendar/eventCode/MusWeb
That would be the main museum I'd be concerned about other than Eiffel Tower. I've not kept up with the ticketing information for them so go to the official website and see what things look like. The crowds are not anything like what they were pre-pandemic.
A word about the Museum Pass. I used to always get that for some of my Paris days but for me it's not been as good a value when they cut back and you could only enter one time per museum as well as needing timed entries for some of the bigger and more popular museums. If you have to get a timed entry you might as well just buy a ticket for that venue. YMMV on this depending on what you plan to see. I used to use it to go in to smaller museums...I'd think, well, I've go the Pass so let me drop in to "X" museum.
Personally I'm a huge fan of booking a tour with skip the line tickets. I know that it might be a little spendy sometimes but it is 1000000% worth it every time. You feel like you can actually appreciate what you are seeing so much more! But if you are going on your own make sure that you request the permanent exhibit only if you want to save some money. A lot of the museums will have some kind of feature or special small exhibit within the museum that they charge to see but the permanent exhibit is free! Musee Carnavalet is a great example. Definitely a great pick for a drop in with no prior reservation and totally free!
The big two, however, I highly recommend a tour so you don't feel completely overwhelmed and you leave feeling very fulfilled.
Louvre (this tour was incredible and I can't say enough about our tour guide, Adam 10/10 recommend): https://www.tripadvisor.com/AttractionProductReview-g187147-d12367018-Skip_the_Line_Closing_Time_with_the_Mona_Lisa-Paris_Ile_de_France.html
Orsay museum: https://www.airbnb.com/experiences/363169