Youre question is confusing. Are you looking for more bases than La Roche-Guyon? Or will it be just this place?
La Roche-Guyon is located in the Vexin region, what is actually a natural regional park and with the building restrictions it has kept it’s original character pretty well. The countryside is charming, it’s an attractive area to drive around. Within easy reach you can go, as many do, to nearby Giverny for Monet’s house and it’s gardens.
More nearby villages like Amblevlle, Omerville, Quiry-en-Vexin are charming little places worth a stop or driving through. Domaine Villarceaux with it’s 18th century château is a beautiful park good for a relaxing stroll. Entrance is still free I think.
More driving is needed for going to Rouen, Lyons-la-Fôret and Auvers-sur-Oise where Vincent van Gogh spent the last days of his life. Château d’Anet south of La Roche is worth a visit to my opinion too. Further the ruins of Château Gaillard with it’s stunning view of Andelys and the Seine Valley at the background. Maybe a bit too far, but Gerberoy west of Beauvais is certainly worth considering.