It’s with the utmost respect for Ed’s brevity which I greatly admire but am apparently unable to emulate that I’ll share my thoughts . . . which is fairly presumptuous on my part given my vast travel experience in Paris (a mere 5 days, albeit quite recent). As to (4) (Latin Quarter) – just plan to walk that area any evening – everything (shops, restaurants) is open very late and the people-watching is great. On another evening, walk the Marais or another neighborhood. As to (1) Sainte Chapelle, I like the suggestion of an evening concert. Note that the windows are under restoration so the rose window and some others are not visible; I also see on their website that they’re closed 4/2 ‘til 2:15pm, so keep that in mind.
Wednesday, 4/2: After you arrive, get into the city and checked into your hotel, go ahead and do the Hop-On/Hop-Off – with my caveat that you DO hop OFF! Get out, walk around, get fresh air – and you’ll be able to cover at least two of your must-see items (2) and (6): L’Arc de Triomphe and Champs Elysees. Note however that the L’Arc has quite a bit of scaffolding on it (at least it did 4 weeks ago). Make a note that you’ll want to spend time at the L’Arc de Triomphe du Carrousel – just west of the Louvre as you walk toward the Tuileries gardens. This is a smaller Arc, but it’s beautiful and merits your time and inspection.
Thursday, 4/3: After your morning Louvre tour, I suggest you spend the afternoon covering (3) and (5) Montmartre and Sacre Coeur. Get to the Metro 2 line and get off at Anvers, start walking up the hill, have lunch, enjoy the neighborhoods, and work your way up to Sacre Coeur. When you leave Sacre Coeur, don’t go back down the hill – go on “behind” and explore the neighborhood, enjoy the artists at Place du Tertre. You could have dinner up there before heading back to your hotel.
Friday, 4/4: You have a full day of tours – after you return from Versailles, perhaps walking the Latin Quarter or Marais, or see about a Sainte Chapelle evening concert.
Saturday, 4/5: Your (7) Invalides museum opens at 10am, get there early, spend a few hours, then you have the afternoon open for something else. Now, you could do your (8) Montparnasse Tower, but by this point you might change your mind. By my calculations it costs 2 adults $55 to go up and take in another high-vantage-point view of Paris. There’s a nice 8-minute youtube video where you can take a look at what you’ll be seeing and decide if it’s worth your time. You might have more fun going into the Galleries Lafayette Department Store, take the escalators up to their rooftop terrace and takie in the view from there—it’s very nice, and free! Have a little lunch, a little shopping, find a cafe to sit in an enjoy a glass of wine or coffee, soak up Paris, and relax so that you can enjoy your evening Eiffel Tower & Seine River cruise.
There, now I’ve been able to vicariously plan a trip (not mine) and feel jealous that you’re going to Paris and I’m not. (You'll find ramblings on my recent 5 days in Paris in Trip Reports.) Enjoy!