Some general requirements for "Simple Enough"

Given an area of interest, classify polygons as

Surrounding (completely containing the area)

Intersecting (intersecting the area)

Containing (completely inside the area

Disjoint (completely outside the area)

Disjoint polygons can be eliminated
Intersecting polygons can be split into disjoint and containing polygons
If there is only one polygon, fill area with backround, then scan-fill polygon area
IF there is a singe surrounding polygon, and no intersecting or containing polygons, display the surrounding polygons color
There is a surrounding polygon in front of all other polygons, display the surrounding polygons's color in the area
A surrounding polygon can be determined to be in front by computing the z coordinates of the surrounding, intersecting, and containing polygons at the four corners of the area

It should be mentioned that the Warnock algorithm makes good use of a quad-tree structure.