As you can tell, you can easily cover a lot of the main sites in less than 2 days in Paris. However, if you have a couple of extra days, then I highly recommend spending one day visiting the Chateau de Versailles. It’s impressive, majestic, typically French and the grounds are simply stunning. Take the time to go out there, you won’t be disappointed.
If you’re a big Walt Disney fan like myself, then also take a day out of your trip to go to Disneyland. I’ve been a few times and never get bored of it. I would pre-book tickets because they could be cheaper online and that avoid queuing once you get there. Also, I would get tickets to both parcs because the fun / adult rides are actually in the second parc (not the main one). I would also highly recommend going during the week and out of school holidays to make the most of it and avoid queuing for an average of an hour for each ride. Finally, I must point out that the food there is mediocre and pricey. If you’re allowed to bring your own food then I would suggest grabbing a few things from your local boulangerie before making your way there.
If you’re in Champagne, then perhaps you’ll want to take a day touring Reims and come champagne houses. Reims, the capital of the Champagne region of France, is only 45 minutes away from Paris and worth the trip. The centre of town can be visited in no time – it’s tiny – so you can spend the rest of your time visiting big cellars and understanding how Champagne is made, whilst sipping on some cold golden bubbles. If you’re feeling extra adventurous then hire a bike and get lost in the vineyards between Reims and Epernay, Rilly-la-Montagne or Chigny-Les-Roses. Lots of other big Champagne houses to discover around there… Make sure to double check the train times (or pre-book your tickets) and opening hours of the champagne houses, especially if you’re going on a Sunday. Like most of France, everything closes on a Sunday!