Two days are not much for Paris so you have the choice between two solutions:

The crazy tourist: jump from Eiffel Tower to Le Louvre museum, Arc de Triomphe, Champs Elysees, Moulin Rouge, Montparnasse, Sacre Coeur and you'll drop dead of exhaustion OR

Easydoing tourist: stay at one of these two arrondissements preferrably the 6th,

http://www.parishotels-discount.com/by-area/75006.htm

http://www.parishotels-discount.com/by-area/75005.htm

when out of the hotel, walk to La Coupole (large restaurant with outside terrace) drink something, watch the crowds, buy and browse through the PARISCOPE, probably the best what to do/where to go guide of Paris (€1.-to 2.-).

If you don't mind walking a bit, stroll to the Ile St. Louis, along the Seine and just enjoy the sights.

For nightlife, depending on the budget you'll find everything in the guide. There are crazy places to go, the equivalent of the ex Studio 54 would be the La société des bains or something similar. Very expensive, along the Seine but crazy.

Drop a PM if you want more info.