Houndstooth

This is one of my rare forays into painted canvas. It's really hard!  But she perseveres!  I don't know the artist, but it is Houndstooth Tablet Case from Dream House Ventures.

It's about half done. It's hard to see, but there's a lot of metallics and most of the black is Pearl cotton. Too much black uurrggg. 
Anyway, the 2 areas marked (upper left and right corners) have me stumped. Does anyone have any ideas about a stitch or stitches to use?
The yellow with gray circles I plan to do with nested Jessica's. The black wedge I want to try to use waffles, with lots of compensation.