Eiffel Tower

Nobody can think of Paris without visualizing this giant structure. Anywhere you go in Paris , Eiffel Tower will be with you! You will be amazed to know that this structure was built as a temporary one to commemorate the centenary of the French Revolution. City Planners wanted to bring it down after the ceremony!
You have to to see Paris from the top before and after the sunset. I suggest you stand in line for the tickets 2 hours before the sunset. There are three level and spend sometime in each level before moving to the top. Please have a city guide to Paris with you ( or Print outs from website ) so that you can identify all the city attractions from the top.

Official Website for more details

Arc de Triumphe

This is a Huge Arc ( Gateway of India was modeled after this ) at the end of Champs Elyses ( main Paris avenue).Around 12 roads join the Arc. You can go to the top through the spiral stairs. Dont ever miss this experience. You will get a wonderful view of Paris from here. Take a photograph of Eiffel Tower from the top of the Arc without using the flash ( You will need a tripod or you can keep the camera on the wall using timer )

Walk in the avenue Champs Elyses just to get a feel of Paris shopping. If you are fond of perfumes and want to buy one from Paris, you can do it in one of the shops on this avenue. It will cost you 50 Euros atleast. Take a snap of this avenue either from Arc or from its opposite end.

Louvre Museum

Easily one of the biggest and greatest art museums in the world. People always say that it takes you at least 3 months if you want to see everything there. You cant miss Mona Lisa. Can you? Spend half a day or at the most 1 day here. You will be dead tired by the time you finish it. If you have not read the novel 'Da Vinci Code' yet but planning to read sometime , read it and visit the museum.

Details can be found here .
Info about the attractions discussed in Da Vinci Code

You can take photographs inside so dont forget your camera. Suggest you go here early in the morning to avoid the rush.

Muse d'Orsay

A modern museum. Only if you have time.

Notre-Dame

One of the biggest Cathedrals. You will have a splendid view of Paris from the top of the towers. Climbing the steps is a experience in itself!

Htel des Invalides

Originally built to house the disabled, it houses Napoleans tomb now. Also has a army museum. You can skip this if you dont have time.

Sacre Coeur

One of the big churches of Paris and a famous tourist attraction. You will have a complete view of Paris from here as it is towards one end of the city.

La Defense and Tour Montparnasse

La Defense is the business district of Paris. One can see modern architecture here and some strangely designed buildings. It houses most of the buisness groups. This should be seen during day light
Tour Montparnasse is the city's tallest office building. This is more like Empire State Observatory in NY.

Versailles Palace

Remember the Treaty of Versailles ? That signified the end of World War I. This is one of the most beautiful palaces with its art gallery and its huge garden. This is far from the city compared to other attractions.

Disney Land

Easily takes up one day. Visit only if you must !

Boating in River Seine will allow you to see all the attractions again!

2 days Trip - Start with Louvre Museum. Finish it by 2 pm and walk towards Eiffel Tower so that you can walk through Champs Elyses. Come down from the Tower after watching the city in night. Visit Arc de Triumphe and wind off for the day.

Second day - Visit Versailles Palace and by noon plan to be in Notre-Dame. After that visit La Defense and Tour Montparnasse. If you still have time, you can see other attractions as well. Sleep only for 4 hrs and be prepared for a thoroughly tiring 2 days. Its well worth it. After all you dont visit Paris often !!

I will add later if I have forgotten something!