Cachan is a little town really close to Paris, less than 10 minutes by transport. Convenient, quiet, cosy apartment which is indeed an ideal place to visit Paris and Sceaux (Beautiful castle and Park) 3 minutes walking from the station "ARCUEIL CACHAN", B line which takes you shortly to airports (CDG and Orly), Denfert Rochereau, Chatelet, and Saint Michel (same line) and other places connected to main and most tourist interest areas.
Otherwise, there is a bus (n°187) which takes you to Paris (Porte d'Orleans) within 10 minutes.. The bus stop facing my residence. If you decide to rent a car ( though I do not advise you if you plan to visit Paris, train, buses and underground are better for that..), You can park it for free under my residence in a very safe place.