Paris is very smart (très chic, actually) and it's just over an hour away.
The Eiffel Tower is a must-see, and not just in the daytime. To follow the tourist trail, stick to the banks of the river Seine – most of the big attractions: Notre Dame Cathedral, the Louvre, and the Pantheon are nearby.
Venture wider, along the Champs Elysees to the Arc de Triomphe, drink beer in strange glasses in boulevard bars, or live it up a little and enjoy the frills of Moulin Rouge: Paris always lives up to its reputation.