I suspect your conference is in La Défense or adjacent to it, in which case anywhere along metro line 1 would be good.
To stay close to the La Défense area, I would suggest Les Sablons in Neuilly. Not technically Paris, but feels like it, and there are a few hotels in that area. 2 stops further into Paris (Argentine), rue des Acacias is also really pleasant, with good restaurants all over.
I would skip over the Champs Elysées area, and consider Tuileries / Palais Royal if you want to be more central in Paris, but your commute to La Défense will reach 30 minutes, and it is crowded in the morning.
If your conference is elsewhere in Courbevoie, near the train stations on line L (Courbevoie or Bécon-les-Bruyères), then the safest bet is to be close to Gare Saint Lazare. Note that line L has a confusing service pattern: there is also a train station at Pont Cardinet, a nice area, BUT the trains that stop at Pont Cardinet do not serve Courbevoie (they serve Bécon, though).