It usually happens that I'm still touring a museum when hunger pangs hit, and I'd much rather stay in the museum than leave, find food, and return. My experiences with museum cafés in London have generally been good. (I remember a particularly good chicken and leek pie at the Natural History Museum.)
Does anyone have any thumbs-up or thumbs-down info for museum cafés in Paris? I've heard the one in the Musée D'Orsay is pretty good.