Paris at Night Suggestions
I would start my photo tour by doing sunset at Basilique du Sacre Coeur de Montmartre. Beautiful! You can see the Eiffel Tower from just about everywhere, so keep your eyes peeled for sexy reflections and framing opportunities. Notre Dame and the Louvre are within walking distance of each other. Tons of other photo ops. Use the Metro and your feet to get around--works great! Avoid taxis or rental cars.
Steer clear of political rallies or demonstrations. A photojournalist friend of mine was seriously injured and had his gear stolen when he stumbled across these entitled thugs. This guy covered war zones without a scratch!