Go native and sleep under the bridges !! Cheap and fun !!
Rivoli area is in, loads of bars, restaurants, clubs, etc. You're also on the main shopping area. There's an Ibis, Sofital and Orion there.
Other side of tiwn would be around the Champs Elysee. More expensive (Mariott, George V), but there are some smaller and nice hotels as well. Bonus is that on the other side of Etoile is Ave Grande Armee, and every motorbike manufacturer is present there!!!