As a 1st time International passenger you might want to consider a slightly longer layover, especially at ATL. "Spring" can definitely come with fine weather, both in Paris and the US, but if you have bad luck "spring" weather can also include fog, winds or even snow. Delays do happen and your 1h 31m could in theory be reduced if you encounter delays. It is do-able (I would do it!) but if you lack experience navigating through large airports (ATL being huge of course) then you might appreciate a stress-free layover.