Alright, finally got some rest and some clean hands to upload some of the pics from the prep and cook.
With the trimming, my goal was to trim away whatever was required to get the brisket to lay flat, any hangy bits, and any darkened/bruised/unrenderable meat. I feel like they cook more uniformly for me when they're all one approximate thickness.
Regarding the "Excel vs Black Canyon" briskets, turns out that I did end up liking the Black Canyon briskets better, though they both sliced and tasted great.
What I liked about the Black Canyon ones is the direction of the grain in the flat in relation to the point - made it very easy to slice. I could definitely recognize which ones were the Black Canyon briskets after cooking them.
I was very happy with the results of the USDA choice "angus" beef that Sam's has.