I am going to el salvador for 2 weeks and will have 3 free days to spend somewhere?

I am heading to the north (Chalatenango) already on this trip, and I already know San Salvador and La Libertad area. I am looking to head EAST (not San Miguel) to see some new things I have never seen before, but would consider west to the coffee country or north of Santa Ana to visit. I would consider some historical site near San Salvador, but most likely want to see a completely new area/place in the east. cooler and greener and small town/village would be nice. I am an adventurous traveler, so don't be afraid to suggest anything. I have been to El Salvador 10 times but mostly in Chalate area and in the capital.