Le Méridien Étoile is fairly average - the upgraded rooms aren't bad, though, and the jazz bar is excellent (if rather pricey). It's not in the centre, but it well positioned for the Palais des Congres and the Air France coach from Roissy. It's opposite Metro line 1, too, which is handy.

Personally, I've given up on chain hotels in Paris (K+K Cayré notwithstanding) and tend to go for boutique hotels instead. The Special Places to Stay guide is excellent.