To go to Santa Elena, we took the road from Tilaran (north) and it was pretty bumpy. There was no need for 4WD or high clearance, but the road was dry (it may make a difference if/when the roads are soaked wet). The road was about 35 km of bumpy dirty road.
When we left the Monte Verde area, we took the road south, going to Sardinal, and it was much better. It was still a dirt road but it was much less bumpy and much shorter (~15 km).
If you are considering going to Santa Elena/Monte Verde, you may want to use the road from Sardinal.