I wouldn't call Gaspard de la Nuit relaxing... it's one of the most nerve-wrecking pieces in the entire piano literature, and not only for the pianist!
But if we're talking French and comfy, let's go for the obvious one:
Transcription in the light of harpsichord technique for the modern piano of the chromatic fantasia of J.S. Bach, followed by a fugue: and other piano music and transcriptions by Kaikhosru Sorabji
Pianist: Michael Habermann
Godowsky can be stimulating yet relaxing at the same time. Try the set of pieces called Triakontameron (it includes Godowsky's greatest hit, Alt Wien). There's a fair amount of contemporary piano music which is good as accompaniment for reading or just doing nothing. Stephan Moccio and Joep Beving are two I've enjoyed in that way.