A bit of work done...buttoned up grading the ground, and laying some ground cover, and gravel for drainage. Then the floor system went together. 2x8s...These are *plenty* solid. I'm pretty happy with the choice...and glad I didn't have to dig& level four more piers! I can eke a bit of vibration, sure. But it's a pretty stiff, high frequency vibration, and definitely adequate.
Screw up #1 on this project is that I didn't notice that my built-up beams kind of "peel away" from each other at the ends. So, when laying the sheathing, trying to true-up the floor sheathing square, I discovered that I hadn't accounted for the added width at the corners. I
didn't catch why till it was too late, and all the floor sheathing was nailed down. When trimming down the sheathing, I discovered that the beams stick out by 1/2" on the ends. Then I realized, that's where the bit of slop in the 1/8" gaps I was trying to maintain in the sheathing install was coming from; there was actually a slight arc to the sheathing layout as I tried unwittingly to make it follow a slightly curved beam. When I put up my two long walls, I'll need to make up about a quarter of an inch on either side, at the floor.
Screw up number two on this project is that I didn't really have a good idea how I was going to anchor that 6x6 column at the front right corner of the shed. Now that I've sorted out something in my head, I have some undoing to do on that exposed corner.