One last "official" post from me, and I'm calling this build DONE!
My dog holes are all 3" from the edges. The six holes to the right of the vise are spaced 15" apart. My holdfasts have a radius of 13", so this gives good coverage.
Here I have used extended dogs with Bench Cookies
. This can act as a second work surface (using my front 2 holes, I can run this the full length of my bench) or just elevate a piece for sawing, finishing, etc. Rockler had a sale awhile back - the set I got has x4 cookies, cone tips, and extended dogs. Must've been something they pieced together for the sale, because I don't see it on their site now.
The back 4 holes are centered over the leg, which is perfect for mortising. Given the arrangement of these back 6 holes, I should be able to hold just about anything.
A note on the Gramercy holdfasts - maybe it's because the bit I used left such a smooth finish in the holes, but I had to sand my holdfasts with 80 grit so they would grab. Specs on the holdfasts say they will work with a 3 1/2" thick bench, which is what I have, but they absolutely would not hold until I sanded them. They work great now though!
Thanks for the support and help, everyone. I definitely couldn't have done this without you!