The two of you will have a great time. Every time I go, I see a lot of American mother/daughter combinations, usually while standing in line for a museum entry (or trying to figure out how to bypass the line - one of the primary perks of the Carte Musees & Monuments AKA the Paris Museum Pass).
If you want to visit many museums, the Carte Musees & Monuments is a money and time saver. You can get a three-day pass for 36 Euros. You do not have to stand in line; you can walk to the front and show the guard your pass and gain entry; you can also visit the same museum every day if you want. My favorite museums are covered (except for the Marmottan) and include: the Musee du Louvre (Michelangelo's Slaves, Venus de Milo, Winged Victory, Mona Lisa, crown jewels, Napoleon III's apartments); Musee de la Mode et du Texile (fashion); Musee National du Moyen Age - Thermes de Cluny (Lady and the Unicorn Tapestries); Musee d'Orsay (Impressionist paintings); Musee National Picasso (Picasso of course);and Musee Rodin (the sculptor's home and garden filled with his works and his collection of paintings - Van Gogh, Monet, Munch). In addition to musems, the following places are covered by the pass: Arch de Triomphe, St. Chapelle, Towers of Notre Dame, Crypts of Notre Dame, Pantheon, Napoleon's Tomb (Invalides), Conciergerie, and Egouts de Paris (Sewers of Paris). Versailles - the chateau and the Trianons - is covered also.
A self-guided tour of the Opera Garnier is worth a visit (gorgeous and historical). The homes of Victor Hugo and Honore de Balzac are open to the public and are free!
We had a boat ride on the Seine included in a cheap package that we bought a couple of years ago and went on the last boat of the day to take advantage of the sunset (it had snowed that day and was still really cold; the boats are heated).
The best views of the Eiffle Tower are from the top of the Arch de Triomphe and from the Trocadero. At the Trocadero viewing area, you will probably see lots of brides being photographed.
I cannot recommend places to eat but be sure to pop into a boulangerie and get fresh croissants, pain au chocolates, and a baguette; your purchase will usally be wrapped in lovely tissue paper. Visit a patisserie for pastries but not for bread. Crepes with nutella make a wonderful snack. Roasted chestnuts smell wonderful but taste icky. Ice cream is exquisite and worth the 2 Euros per dip; exotic flavors such as violet are often available.
If you must drink soft drinks (I am addicted to diet coke), buy them at a grocery store (a supermarche if possible) for a reasonable price. I buy 2 liter bottles of generic coca cola light at Champion for 0.34 Euros and refill my 0.5 liter bottle.
Paris is wonderful for just walking around and admiring the architecture, the clothes in the shops, the men, and other fascinating sights. I said in an earlier post that I really enjoy looking in the pet stores; you will be amazed at the prices.
Hope this helps.