A quick question for travelers.

I find myself going to Russia and Kazahkstan in a couple of months, and have an opportunity for a long layover each way. Which city would you more experienced travelers recommend for quality sightseeing and experiences? Keep in mind, I must maintain a security clearance at work, after coming back!

Frankfurt, Amsterdam, or Paris?

Paris, hands down. You have the National Arms Museum, the Louvre, Napoleon's Tomb, the Marsielles, the Eiffel Tower, the list goes on and on. Not to mention the food the French are famous for. They also have all the night life you could want if you are so inclined.