I decided to go for the Yellow Jacket spray killer due to cost. The traps were $10 to $15 and another shopper assured me they don't work. The spray was only about $3. I have pictures of the nest as it looked yesterday afternoon - here are the culprits:

If you want to see the size of the nest in comparison to the fence (since the picture above makes it look slightly larger than it actually is) then view this picture of the fence and the nest from further away. The follow-up story is shortly forthcoming.