For The Kids, Paris, France
If you're looking for destinations in Europe, Paris should be near the top of the list.
Like any trip, be sure to plan ahead. September is the busiest month for tourism in Paris, so book your hotel room well in advance. You can visit after September, of course, but if you do, pack extra raincoats and umbrellas, because you will definitely get rained on.
Upon arrival, kids with any sense of Europe are going to want to see three very important sites.
First, the Eiffel Tower. Hated when it was built as an ugly monstrosity, it's now one of the most famous landmarks in the world. There are four lines to get onto the tower, so look for the shortest one. Don't be afraid to haggle over souvenirs underneath it, and make sure to go to the top of the tower at least once.
Second, thanks to Victor Hugo (and Disney's) famous Hunchback, don't miss Notre Dame Cathedral, where Napoleon took the crown out of the Pope's hands and crowned himself. If you don't mind a bit of a wait and a climb up 386 stairs, the view from the bell tower is worth it.
And third, the Mona Lisa. This will require a visit to the Louvre, which is like visiting another city inside Paris. Fortunately, like all of the museums in Paris, anyone under the age of 18 gets into the Louvre for free. Buy your tickets online, to avoid a long wait outside the museum (or, if you didn't get the chance to do that, use the underground entrance in the shopping mall. That's where you'll find shortest line).
It's easy to get lost in the Louvre, because the museum is huge. You'll never see the whole thing in one visit, so don't even try. Just follow the signs to the most famous exhibits, like the Venus de Milo and the Mona Lisa, and enjoy the sights along the way.