Some tips & Hints for Paris:
1. Best place to see the Eiffel Tower lit up at night is from the Trocadero. (Train 6 or 9) It only lights up every hour on the hour, only lasts 5 minutes, and dusk starts later in Europe, so maybe only 9:00, 10:00 and 11:00 shows.
2. If you're in Montmarte (to climb or cable car to Sacre Coeur), check out a place called La Refuge des Fondues... Because there's a tax in Paris on wine glasses, they serve their wine in baby bottles. Sounds like fun ;)
3. The best walk I had was in St. Germaine. Pick up a baguette, some meats & cheese and a bottle of wine, maybe some macarons, and head to Luxembourg Garden for a picnic. Don't forget to ask for glasses at the wine shop. Kids float motorized boats and stuff in the pond, but its pretty quiet there. Also remember to pack a knife to cut cheese & butter bread!!
4. Pigalle is a fun place - its where all the sex shops are. Pronounced "Pig Alley". Moulin Rouge is apparently overrated, Crazy Horse was fun, but pricey as well. If you have to see burlesque, this one has a ton of history.
5. the Louvre is closed Tuesdays, btw. And if you go, expect ridiculous lineups. I opted for the Army Museum, with tons of Napoleon stuff (I enjoy that history)
6. Paris was bulldozed in the early 1800's, and totally redesigned by Haussmann... nothing bigger than 4 stories, cream colours, wrought iron railings, wide boulevards lined with trees... do check out any of the Grand Boulevards. Paris is old, but since the redesign, it looks newer than most European cities. Very unique
7. Hop on Hop off Boat is a great way to get around. The river Siene stinks, and is kinda gross. Just so you know.
8. Had dinner at Le Grand Colbert - it was featured in the movie As Good As It Gets, which was kind of cool to see the production photos, etc.
9. Walk the full Champs-Elysses from the Arc de Triomphe down to the Caroussel Arc de Triomphe.
10. There's an unofficial memorial to Princess Diana at the site she was killed. Didn't get to see it, but wish I had. It's at 7 Place de L'Alma (9 train to Alma-Marceau)
11. Have fun! The Metro there is brilliant, just get a pass for the number of days you're there. And a lot of the city is very walkable. Probably not a whole lot you can't find online, but maybe gets some ideas in your head.
Also, they're 240V there, so you'll need to bring a converter for your phone charger (otherwise you'll fry your phones)