Rincon is a quiet, rural area of Costa Rica. We really liked it when we visited. While there, you’ll want to check out Rincon de la Viejo National Park (more info here) and hike to see the volcanic features and also visit Llanos de Cortes Waterfall. You should be fine getting to your hotel with a regular car- the roads are mostly paved in that area. If you do visit Llanos de Cortes Waterfall, you might want 4×4 for that because the road is dirt and gets steep but we’ve seen regular cars access it to if you’re feeling adventurous.
If you need more help, we do offer itinerary services where we could review your travel plans and answer any additional questions you might have. There’s more info on our website here.