I have the same question ! My situation is as follows.
I have done :
- The Ravaged Beach - Forgotten Chapel - Druid Grove area. So, probably almost all things east of the bridge to the Blighted Village.
- The Blighted Village (surface + cellar), the Goblin Camp (outside), the Goblin Fortress (only the level with the 3 leaders), and the camp celebration.
I have avoided as best I could :
- The Whispering Depth.
- The Wetlands.
- The Risen Road.
- The Underdark.
It was my hope that doing at little as possible outside the main path and stopping at celebration was about 50% or 66% of Act 1 (which apparently is just Act 1A, so that's great). Is that roughly correct ?
The following areas have coherent, finished storylines in Act 1:
- The Ravaged Beach and
- The Druid Grove
- The Wetlands (MY FAVOURITE)
- The Blighted Village
Incomplete Areas that will make your cliffhanger-allergic heart scream in pain, in order of completion:
- The Goblin Camp (too many loose ends / unimplemented solutions, although it is really cool to navigate)
- The Zhentarim Hideout (80% complete, too many loose threads, but it's a small area with a great vendor)
- Waukeen's Rest (busy, difficult to navigate for very few questlines, it looks like a set-up at the moment).
- The Risen Road / Tollhouse / Githianky storyline
- The Underdark (except for the Myconid Colony arc)