Things to visit in paris

I am not a frequent traveller but I have travelled most of the big cities in Europe. It was about six month ago I trvelled last time and I am planning to visit Paris after one year. I don't know much about how to travel there. But I know that there are lots of places to visit. I have specially heard a lot of the eifel tower, hotels in paris and the night life of Paris. Some of my friends visited paris last year and I missed that. I've  also seen paris being mentioned in the fashion topic also. It seems like a very fashionable city. Musee d'Orsay is a museum about which i've heard a lot from my friends and other people. This museum holds few of the best example of arts in the world how over its collection cosists of more recent works. Some of the artists features in that musuem are rodin, degas, renoir etc. 
                 There is several good Hôtels en Paris according to my friends. They booked hotel before leaving and they enjoyed the nightlife fully. I also came across a good site which serves booking in Paris hotels. Cheaperthanhotels offers last minute and year round accommodation at prices often less than direct prices. I hope I will be able to do this travel as soon as possible, I have to finish my exam first.