1. Go to the Rila monastery. It is about 2 hrs away with a car/bus. It is in the Rila mountains and the nature around is magnificent. most beautiful season is Autumn/Fall.
2. Go to Plovdiv. it is the second largest city in Bulgaria after Sofia. It has beutiful center with an old town situated on hills.
3. Take the train and go to Cherepishki monastery. It is north of Sofia on the river Iskar. The canion of the river is amazing. You can eat bob chorba (beans soup) at the monastery about 7 years ago