I am planning to visit Guilin with my Wife during Aug 2 week. Will be flying from Hangzhou and would like to cover the must see places in 4 days time.

Hi, here is my general suggestion for your trip:
D1: Take Li River cruise to enjoy the nice scenery. Spend your afternoon in Yangshuo.
D2: Yangshuo West Street and Impression Sanjie Liu cannot be missed.
D3: it is suggested to go to visit Dragon's Backbone Rice Terraces in Longsheng.
D4: You can go to GL to visit the attractions there or have a Dong minority short trip in Sanjiang. Then go back to GL.