Skip the line... Or buying directly for activities in Paris?

You should really purchase Catacombes tickets in advance and print them out.
Your child doesn't need a ticket, nor proof of ID. You can provide your drivers' license for the audioguide.
The dedicated entrance is in front of the roped-off line. Don't make the mistake of getting in the "real line".
You can't "skip the line" - you have to go through Security first. And you shouldn't bring any backpacks or messenger bags that exceed 40 cm x 30 cm. They will be confiscated.

there is no such thing as a special 'skip the line ticket' that only vendors have. They have the exact same tickets you can buy yourself at FNAC or on line. Whether you 'skip' the line depends on the site. At the Eiffel Tower, a timed ticket gets you on a special elevator at about the time on the ticket; it affords no advantage at the elevator from floor 2 to 3 though -- everyone is in the same line. At the Louvre a timed ticket allows entry at the time at the Pyramid and any ticket lets you use the shorter ticketed/pass line; we have found the Carrousel entrance faster than the Pyramid line for those with tickets; we have visited the Louvre a couple of dozen times and never encountered huge security lines at the Carrousel entrance; on one occasion we had about a half hour wait to both clear security and then buy tickets; all other times were very fast. At the Musee d'Orsay those with tickets use a different door for security which often has no line and in high season a much shorter line. At Versailles everyone is in the same security line and so tickets only offer an advantage once you clear security; most of the people in that long line will have tickets. Get there at least half an hour before the Chateau opens to be close to the front of that line. At Ste. Chapelle, generally everyone waits in the same long security line. At the Notre Dame Tower, you reserve a time slot in the morning of the day you visit and return at that time; having a pass doesn't make it faster. For Monet's house at Giverny your ticket allows you to use the shorter group entrance or to just walk in at the main entrance next to the ticket line.

but it doesn't make sense to pay a vendor extra for the same ticket you can get yourself on line.

No one is going to make you prove your 11 year old is not 18; if the special ticket at the Catacombs is for those 'under 12' then she will need ID just in case; student status is irrelevant; the passport is the correct ID and I would carry copies of everyone's passport as a matter of course; she will just walk in with you at most sites like museums which are free to her. If she carries a passport it needs to be well secured, perhaps in your neck wallet or a money belt under clothes; you are unlikely to have to show it, but if you get an officious ticket taker you will feel more comfortable knowing you have it.

For the Notre Dame Towers there is a Kiosk near the entrance, Left Hand side facing Notre Dame. You can print out your scheduled time beginning at 07:30 that morning. You can also use their App, JeFile, and book it from your phone starting at 07:30. Even with the Paris Museum Pass you need the scheduled ticket time for entry.

http://www.tours-notre-dame-de-paris.fr/en/News/No-more-queuing-to-go-up-Notre-Dame

Enjoy your trip.

WOW thanks! I was worried I was going crazy because I could not figure out why it was so vastly different prices.

I truly appreciate the info on not needing any further documents for the children..
I love all your experienced help everyone!

This saves a few dollars for more dollars crepes and gelato! Yum

I would strongly caution against carrying your passport or your child's with you, at any time (except for when you will need it to cross borders of course). I can't imagine anyone would actually ask for it, but if you're concerned about needing to prove age, you can always make a copy of the passport and carry that with you instead. 18 is typically the cut-off age for free admissions and reduced rates in France, anyway.

FYI, we run study abroad programs, and beyond telling our students to never carry their passports, we always advise them to make an electronic copy of their passport that they could access easily if needed (i.e., in your email). It's extremely helpful should they need to replace it abroad.

Thank you for the suggestions of making copies of our passport available via email or some protected way!

I am not going to worry about it she doesn't look 18... even though I am sure she would wish people would think she was 15 at least..lol.

Hi abowen, you walked right into the passport/no passport discussion and you will get different and conflicting responses. I carry my passport at all times when traveling, stored safely in my money belt. Do whatever feels right for you. Consider the consequences of replacing a lost/forgotten passport.

If possible, purchase any advance tickets online from the site's official website. My advice - buy Eiffel Tower tickets in advance. If you are unable to get advance tickets, consider a vendor like Get Your Guide tours to buy a ticket for a one hour tour and skip the line ticket.

Consider buying train tickets in advance, in some cases you will see significant discounts.

You can purchase the Paris Museum Pass once you are in Paris from one of the smaller museums (Rodin, Cluny, Orangerie), no need to pay extra shipping to have it mailed to your home.

We did not find a benefit to purchasing advance tickets for the catacombs. Get there a hour prior to opening. Getting up and out early is good advice for most "must do" sites. Beat the crowds!

Hope you have a wonderful time in Paris!