hi, we stayed at the Lenox Montparnasse, in the 11e in Montparnasse, it was awesome. you can see it on trip advisor
http://www.tripadvisor.com/Hotel_Review-g18714 7-d235575-Reviews-Lenox_Montparnasse-Paris_Ile _de_France.html
It was great value for money, but as all hotels are in Paris, the rooms are small. We had a 'club' room and was well worth the extra money.
It about a half hour walk from the Eiffel, but there are tube stations at both ends of the road near the hotel so you can jump on there, although the walk is a great way to see the city.
The hotel is in Montparnasse which is full of restaurants and life. Also the Tour de Montparnasse is a MUST! its a bit office tower where tourists go up to the 56th floor and get absolutley breath taking views of Paris. You get a guide book and it shows you where all the 'sights' in Paris are when you look from different sides of the tower. Awesome views of the Eiffel, the Invalides, Arc de Triomphe, Concorde, Pompidou Centre and so on.
Sorry to go on but this hotel made our trip, so did the Montparnasse Tower, have fun, im jealous!