We used to live in the Essonne near Brétigny sur Orge. You have the RER ligne C which is safer than the ligne D - 35 min to Paris. A few stops further south you are practically in the country. Check out towns like St Michel s/Orge, Plessis-Paté, Marolles en Hurepoix, Arpajon, St Genevieve des Bois .... even as far as Dourdan. Other advantages are proximity to A10, A6, N20, Francilienne.. Avoid Evry, Etampes, Grigny which can be trouble spots. Housing is not cheap but this is to be expected of pleasant safe places near Paris.