How about you list off which attractions seem most appealing to you and we can chime in with some advice on how long they take and which ones are the best. I can tell you what I enjoy the most in Paris but what does it for me may not do it for you. Also, that will give everyone an idea of your tastes. Like do you want museums or churches or gardens and outdoor spaces or the opera or chateaus?

Also, as was said, you'll have no problem getting a taxi at the airport. There will be drivers standing inside asking if you need a taxi or just walk out and look for one. As for getting back to the airport, just have the hotel call a cab for you, it's quite easy to get one. It should be about 50 euros.

My personal favorite is Musee D'Orsay. I'm really into art and architecture so it was quite the treat. I think I was there for three hours or so. Versailles was far too crowded and the weather was not good, it was my least favorite attraction. It's a long trip, too. Well, the train ride isn't that bad but then you factor in the walk to get there and then seeing the house and gardens and it's a full day. I might go back on a future trip but it has to be on a day with better weather and during the week. The Louvre is amazing, of course. Tour Montparnasse is nice because you can see everything, especially the Eifeel Tower. The worst part about going to the top of the Eiffel is that you can't see the beautiful structure you're standing on. It's also cheap and very easy access.