If you can spare the cash and time, do the Paris hop on/off bus. This will give you a good overview of Paris within 2-3 hours if you don't get off anywhere. The audio commentary itself is useful. Can't remember how much it was, around 15 euros I think?
Another alternative is to go on a walking tour, there are several to choose from depending on what you like. I like doing this because it gives you a more personal touch (compared to the bus or a regular scheduled tour). If you're adventurous do a Segway tour
I stayed at one of the hotels near Gare du Nord, saved me time instead of lugging bags around the city after getting off the train. Staying in one place is fine, in fact, just staying in one hotel and just taking the train to Disneyland is ok too, although you'll be dead tired coming back. Check the DRP hours online, they close early during the winter which is very annoying. I second the suggestion of buying the tickets online, saves time when you get to the park itself.
Good luck and have fun!
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