1. Cherrapungi- living root bridges (1- 2 days) 2. Dawki river for the crystal clear waters (day tour), 3. Mawlynnong- cleanest village of India (day tour) 4. Shillong elephant falls (day tour from Shillong).
You can start your trip from Shillong (1 day tour), Next day (day 2) you can cover Dawki and Mawlynnong on the way to Cherrapunji. In Cherrapunji (day 3 and 4), you can cover living root bridges trek and Mawsmai caves. I can help you with details if you want.