In Paris now

At none of those should you need an advanced ticket.

The Crypt you should be able to walk up. The charge I think is for the Virtual Reality display at the beginning? It does look like there is an exhibition that starts tomorrow but I would just go and not buy online for this.
(And you do mean the Archeological Crypt under Notre Dame and not the Catacombs, right?)

Carnavalet is free. They are closed on Mondays. If there is a special exhibition there is a charge but there is plenty to see in the free collection part. No timed entry needed. Just go.

Arts and Metiers should not be sold out either. There is a charge to enter but you should be able to buy at the door.

Thank you Pam, will follow your advise.

Ellen,
You might consider the Cluny Museum....open Tues through Sun, 9:30 to 6:15, 12 euros per adult. We did not reserve last May, and I don't believe you need to reserve an entrance time. It's one of my favorite museums, not just in Paris, but out of many I have visited throughout Europe. Not too far from Jardins de Luxembourg and walking distance from the Musee d'Orsay. Have a great time in Paris!

I second Nissim de Camondo. Love it.

Arts et Métiers is definitely a "walk-up" place and it's never busy. I do not even think you can buy advance tickets at the moment according to the museum's webpage, hence the impression that you are "shut out".

The last time we went to the Carnavalet they required advanced tickets; the tickets were free but they were required to be booked in advance. Things change and COVID disrupted everything so always wise now to check with the official web site.

The Crypt is never 29 but that sounds about right for ;the VR experience Eternelle Notre Dame which IMHO is a must see -- 45 minutes sgtroll through 12th century Paris as Notre Dame is being built. Really quite wonderful.

Louvre may book up in advance. We had to change our goals for Hotel de la Marine as it was booked up when we wanted to go -- so good to check ahead .

I have never seen the Nissim Comandor the Asian Museum nearby crowded. And have always been able to just walk into the Petit Palais - you can buy special exhibit tickets inside if desired. (same with Carnavalet except entrance tickets should be booked ahead)

I've noticed an increased need for advance tickets in the past year or so in other major cities. Some places that I expected to be able to walk up to and buy tickets required purchase a week or more in advance.

In October 2021 the Carnavalet did not require advance tickets. Tickets were only required during the height of covid.

Susan, yes, that was my experience as well in April 2022 at Carnavalet. No timed entry. Free admission unless you wanted to add on a special exhibition. In the past right after things opened up after Covid and the museum reopened after the reno you needed a timed entry and cued in chutes in the courtyard.

Update. I followed Pam advice and showed up at the Crypt ( 9 euros),Carnavelet,(free) and Arts in Mieters had no problem.

Oh yea! I am so glad you got in to those 3 museums! All 3 are really interesting and all 3 very, very different!

Ellen:

The Carnavalet is free. The Picasso Museum does not need reservations