This Parisians hate Americans is BS*. Spent over 2 weeks in Paris over the last few years and didn't encounter any more assholes than one would in, say, New York or London. Don't be a jerk, respect their customs, learn a few French phrases and make an attempt. In almost every case they'll slip right into English and you will be fine. Remember, with all of the problems they've had, tourism is down and they want and need your money. I've also traveled around the Burgundy and Champagne regions; the French do not hate Americans. They do, however, hate loud, obnoxious, "You'd be speaking German if it weren't for us", jerks.
As said above, the Louve is huge. Yuge! A full day likely isn't enough. We also love the museums Orsay and L' Orangerie. Notre Dame is great and Versailles is incredible. Oh, do some research and you'll eat really well, too. Agreed the Eiffel Tower is crowded but you are in Paris so.... Don't miss Les Invalide, burial site of French soldiers (former hospital) including Napolean.
Have a great time!
*Parisians can be dismissive of anyone who isn't a Parisian. Don't let that bother you. Embrace it.