You have many options when it comes to finding a place to stay in Paris. When I visit I like to stay just outside of the city in Marne La Vallee. The reason is that it is much less expensive than staying in Paris proper, but also because it is beautiful in the area. The rolling hills and open spaces are a wonderful way to relax after an action packed day in Paris. The great thing is that it is well connected to the city via a quick train ride.
If you are planning on visiting Disneyland Paris while on your trip, there is a train station right at the entrance to the park that will take you into the center of Paris is just a few minutes. In fact when I stayed there recently I found a great hotel hotel about a mile from Disneyland for about $65 a night. The hotel included a free shuttle to Disneyland, which also meant a free shuttle to the train to get into the city. I cannot recommend the area enough, its perfect.