Catacombs in Paris

The issue with this ticket is that there is only a certain number of people allowed in the Catacombs at any given time, for safety and security reasons. If you purchase tickets for a specific time, and the group ahead of you hadn't cleared out yet, you'd still have to wait in line.

The best advice from those of us who've been here is to get up early and get in line before the Catacombs open.

To decide for yourself whether or not it is worth it, I recommend having a look at some YouTube videos. It's a long climb down, a long walk with nothing much to see, then a few rooms with bones stacked up, then another long walk and a long climb up. It is definitely not for the claustrophobic, or anyone who isn't in reasonable physical shape.

This attraction only recently became popular because of a "Blair Witch"-type horror film, but most of that was shot on soundstages, not in the actual catacombs.

The lines can be long. We arrived right around when they opened and waited 3 hours (in July). I don't know about tours or promises of reducing waiting times. I have seen posting where people complained that they signed up for offers to reduce waiting times and still waited a long time.
Was it worth it? That's a matter of what your interests are. We went only because it was on our granddaughters' "must see" list. I'm glad we went but wouldn't do it again (regardless of the wait time).
I would describe it more positively than chexbres did. The history (garnered from plaques along the walls ) was interesting, as were some miniature panoramas built by workers. For my taste, the skulls and bones went on too long, but you're looking at history, not something that was built to entertain tourists. I wouldn't think claustrophobia would be a concern. chexbres is right that you have to be mobile and fit enough to go down, and then eventually back up the stairs, but they seemed to me to be less of a challenge than the stairs at Notre Dame tower, Arc de Triumph, Eiffel Tower, and others.

Last June, my wife and I took the Metro out to the Catacombs and when we arrived the line stretched beyond the block. We didn't try to get times in advance and we just took a shot. Refusing to wait in the lines, we rode the Metro to Notre Dame and went to the Archaeological Crypt at Notre Dame, which I think is actually really different (no old bones, but is a wonderful archaeological site - website at http://www.crypte.paris.fr/en/crypt). For those looking for the creepy bones this won't help, but it was on the Museum Pass (whereas the Catacombs are not) and the Archaeological Crypt had no line and was basically empty when we visited. For us, it was a better option than waiting in a ridiculous line at the Catacombs. Some might find this a good alternative as we did.

Picking up on what Steve said-and straying further from topic-one could also consider heading to Saint-Denis to see the Basilica there, along with the crypt. It's the final resting place of most of the King's of France, and is in an area few tourists see, a spectacular sight. Again, no bones, but far more historic and a lot more to see, imho. There is a modest entry fee for the crypt, but no waiting. A much overlooked sight. Easy Metro/RER ride out there, just outside central Paris.

https://en.wikipedia.org/wiki/Basilica_of_St_Denis

Well, underground attractions might be closed due to flooding, and the necessary cleanup afterwards.
I'd keep checking FaceBook pages of anything like the Catacombs, the Crypte before you buy tickets. FaceBook is a lot easier to update than the official websites of museums or attractions.

Appreciate the suggestions! I think due to the flooding we will hold off on the catacombs and maybe play it by ear when we get there. I think Rome has catacombs too, so perhaps I'll investigate that. I'm really just looking into it cuz my daughter is interested! the Saint Denis Basilica looks interesting.. will keep that one in mind!