A little followup to this...
I've been fiddling with this issue today, and I think that the best yellow/wash combination I've produced is Golden Yellow basecoat with a Gryphonne Sepia wash. I tried both Sunburst and Golden with p3 armor wash with no luck, as well as Sunburst with sepia. I even tried buboc black wash with both colors. The sunburst/sepia combo looks pretty good, but it's still a tad bit dirty and alittle too bright.
So, my conclusion is that if I ever am going to paint a darker color, I will use P3 armor wash. Anything bright needs to be figured out by trial and error.
I diluted the P3 stuff down to a half and half mix of water and it looked pretty good most of the time.