If you want to stay within walking distance of the major sites, you will want to stay in the Marais neighborhood. This historically Jewish neighborhood is known for it's LGBTQ population and has some of the best boutique and independent shopping areas in Paris. Marais is home to several sites itself, including the Hotel de Ville and Victor Hugo's home turned museum. It's within walking distance to Notre Dame and if you can get close to the river, you can avoid cabs and the metro for several of the main sites. The Marais neighborhood is slightly less expensive and less touristy than the St. Germain neighborhood.