My daughter is turning 16 this November, and I would like to take her on a trip of some sort. I've been thinking about either NYC for the week, or a trip for two-ish weeks to Europe with her and her best friend. If I did the Eurotrip we would be going to Ireland, London, Paris, and maybe Switzerland. If we did this, we would be staying in a castle in Ireland (trip highlight), then regular hotels for the rest of the trip. I don't know anything about NYC, so I need help on ideas for that. I need ideas!!!!!!! My daughter loves anything about planes, aviation, the military, music, and the Arabic culture (and every other culture, but she's learning Arabic). She is also quite adventurous, loves to have fun, learn new things, and soak in her new surroundings, and take pictures of EVERYTHING! Her and her best friend also love to shop.

Your daughter and friend are lucky girls to possibly have a Europe trip on the horizon for a 16th bday.
I am not sure where you live, but if there is a choice and budget is open I eould say go to Europe. It will be a trip to remember.
I think adding Switzerland is pushing it though. There are tons of museums in London and Paris that will meet her Military interests...
A few side trips from each city would be ideal such as York or Bath from London to visit some history and Versailles and Giverny from Paris.
You could a bike tour - http://fattirebiketours.com/paris

Have fun!!

If you're planning a two week trip, I would recommend that you focus on a maximum of three countries and preferably no more than three city bases (from which you can make a few day trips), e.g., England/UK, France/Paris and Ireland.

In Paris, visit the L'Institut du Monde Arabe

http://www.greatbuildings.com/buildi...nde_Arabe.html

I think she also would like the Musee des arts et metiers, which is a kind of museum of applied technology. It has the airplane that Louis Bleriot designed and flew across the English channel.

http://www.arts-et-metiers.net/?lang=ang