If I had three nights in Paris with someone who had never been before I would take them to:
- The Eiffel Tower. Go all the way up (I'd recommend the lift!) and admire the view - it's truly stunning. There is also a post office on the first floor, where your postcards get a special Eiffel Tower stamp. I wouldn't bother with the restaurants in the tower themselves, unless you feel like spending some serious money. Oh, and you'd need to book ahead.
- Arc de Triomphe. Walk to the top and check out the view of the city - especially the Champs Elysees. Very pretty. The tomb of the unknown soldier doesn't do much for me, but plenty of people like to see it.
- Musee du Louvre. Decide what you want to see in advance, you have no chance of seeing everything. Seriously. Mona Lisa and Venus di Milo are the things most people "must" see.
- Sacre-Coeur and Montmartre. Gorgeous church, stunning views over the city. The steps are a popular spot for young people in the evenings. The cafes are horrendously overpriced but a nice spot for a coffee.
- Notre Dame and Ile de la Cite. Both are absolutely beautiful, lots of good restaurants on Ile de la Cite as well.
- Quartier Latin. Lots of great cafes, excellent for people watching in the evenings. Careful where you eat around here though, lots of the touristy places are far from brilliant...
If you decide you can't be bothered to trek around to all sorts of sites, the bateau mouches are a good alternative. These are boats that go along the Seine - you can see the Eiffel Tower, Notre Dame, Pont Neuf (oldest bridge in Paris) Louvre and Les Invalides. Go at night if you decide to do this - everything is nicely lit and beautiful.
If you are interested in shopping, go to Galeries Lafayette right behind the old opera house. The food hall is worth a visit on its own!
Hmm, that's all I can think of at the moment (plus it's time to go home from work hehe) but please feel free to ask if you have any Paris related questions. I lived there for nearly six years so I know the city very well, and have been "tour guide" to a large number of friends and family...
Charlotte