My current wip is set in 1809, and takes place almost entirely in England. The next one will be a sequel, still set in England. At some point however I would like to write something set in France during the Revolution, simply because I love the French Revolutionary Calendar so very much.
Unlike the usual Western calendar, which is built from months cobbled together from the self-regard of Roman Emperors, a counting system that has not moved with the times, and some odd gods and festivals and days named after another ragbag of old gods and heavenly bodies, the French Revolutionary Calendar was the product of careful and logical thought by a small committee containing two mathematicians (Gaspard Monge and Gilbert Romme), two poets (Fabre d'Eglantine and Andre-Marie de Chenier) and an artist (Jacques-Louis David).
The months reflect the natural year; the fog of Brumaire gives way to the cold of Frimaire while the wind of Ventôse is followed by the sprouting of seeds in Germinal and their flowering in Floréal. We wouldn't have to worry about whether there were 30 or 31 days in each month - each month is always 30 days long.
The French Revolutionary Calendar ended each year with the month of Fructidor, the harvest month. Then came five days (or six in Leap Years) that were a universal holiday. Each day was a celebration of a different feature - Virtue, Genius, Labour, Opinion, Rewards and, every four years, Revolution.
Today would be 11 Thermidor, in the 213th year of the Calendar. So much more fun than 30 July.