This question if for folks that have seen many catacombs in Europe. Would you go back to any?

The one in Paris is pretty extensive; I'd only go back with a teen or someone who has never been.

If this is a particular interest of yours, the chapter on the Paris catacombs in the book Underland by Robert Macfarlane is superb.

I have only been to the ones in Malta--I could not get very far. I have toured caves and even underground cities in Turkey, but catacombs give me a spatial orientation problem--I have a hard time in maze-like settings.

I’ve been to the Paris catacombs and the ossuary outside Prague in Kutna Hora - Sedlec. I’ve been other places where there are catacombs and have not visited, which says something. The ossuary in Kutna Hora was pretty amazing, the bones are very artistically displayed. Paris catacombs are mildly interesting, but it quickly felt like just endless chambers of skulls (which it is.) It’s kind of an intense space to be in, even if you don’t generally feel claustrophobic. Something about the monotony and size of it all, we were thrilled when we reached the end. Always a long line too, I would not recommend.

My take is, it is a cultural phenomenon that has a degree of shock when you’re not used to seeing it, but it’s not the most fascinating experience. I think places where you really feel the personal connection with those entombed there, like Hallstatt or Palermo can be more meaningful. I wouldn’t plan my trip around one either way.

Bill, I know that you asked for responses only from people who've visited multiple catacombs but given the few responses you've received....

We purposely skipped both the catacombs in Paris and the "bone church" of the Capuchin Crypt in Rome; arrangements of human remains hold no interest for us. Conversely, we visited one of the ancient catacombs (San Sebastiano) out on the Appia Antica in Rome and found the guide's lecture on burial customs of both Christian and non-Christians, dating back as far as 1st and 2nd centuries, to be very interesting. These subterranean cemeteries (there are many of them around Rome but only a few can be accessed by tourists) also display some very old and rare examples of early Christian iconography. No human remains were on display along the tour route; out of respect for the deceased, any which would have been visible had been moved to a level inaccessible to visitors.

Would we do it again? Sure, but are more likely to do one of the others, such as Priscilla or Callixtus, that we haven't seen yet for additional historic value.

Bill,
Of the ossuaries we have visited (Portugal, Czechia, France and Italy) , I am with Kathy. Although the ossuaries were interesting, the catacombs of Rome were different, for all the reasons Kathy stated. Growing up Catholic, we learned about how the early Christians utilized them for hidden services, so their history has a different take for me, and, I imagine for many others. We didn't see a collection of bones, but a place of history.
Of course, walking along the Appian Way that same day was pretty awe-inspiring!

Growing up Catholic, we learned about how the early Christians
utilized them for hidden services...

We were told by our guide that because the catacombs were well known to, and used by, the Roman non-Christian public and authorities, they weren't used by Christians to hide their religious services from persecution. Further research has backed up that claim. One example:

https://www.pbs.org/wgbh/pages/frontline/shows/religion/first/catacombs.html

Kathy,
You are probably right, but I was in Catholic schools beginning in 1949, so that was the theory 75 years ago. I still was moved by the Roman catacombs though.

I completely understand, Judy, They are still sacred spaces. :O)

They are like churches, you see two or three and that's all you need. Although if one is convenient, OK. But don't go out of your way for them after the initial ones.

The catacombs in Vienna are under St Stephen’s cathedral. You enter through a staircase in the middle of the church and exit directly outside around the other end. You have to go with a guide. There is a sign letting you know when the English one starts. Last time we were there no fee was charged. Might have changed.
We’ve also been to catacombs in Rome, Sicily, Prague to name a few.

PS, they also had a night tour on the roof of the cathedral in Vienna. Check their website for up-to-date info.