First, thanks again to everyone for ideas. Between comments here and some more toolbox tour videos, I've got things more organized based on both type of tool and amount of use. For starters, I've decided the cart is likely to have the lid open under all but extreme circumstances, so it can't be closed in its current configuration, but can be with some changes, if need be for transporting.
The latest pic:
I just used the 3/8" socket trays for SAE and metric, and the 1/2" trays for metric. I don't use enough 1/4" sockets to devote tray space. However, I did change up a socket rail and now I have one rail with 8-17mm 3/8" and 5-14mm 1/4" sockets that I can quickly grab and take with me to wherever I am working in the garage. The silverware tray may not be the most space efficient thing in the world, but it has been great for storing the tools I used most often. I suspect its makeup will slowly change depending on what projects are being worked on. My work gloves now all have a permanent home, so I don't dig around looking for them anymore. There's a variety of JIS and flat bladed screwdrivers on the left, and my most used work light on the right.
For the inside of the lid, I am not crowding it too much:
I added a magnetic tool rail, I don't have anything specific that is going there, but I think it will be home for tools that are in use mid-project, so I am not digging them back out of their individual drawers each time I go to the garage, a set of safety goggles, a couple flashlights, a magnetic work light, my metric-inch conversion chart, and in the upper right, a tray to hold my phone. Normally, I leave it by the door to the garage to keep it safe from getting damaged, but now that it has a dedicated space, it can stay closer and easier to access.
The top drawer on the left holds my metric combo wrenches, and top drawer on the right holds additional pliers and vice grips.
I think all those together comprise the tools I am using 75+% of the time in the garage. I've already noticed it taking less time for me to get started when I go into the garage, and less time to clean up when I shut down.
Other drawers in the cart and in my rolling toolbox are still evolving slowly. No target date on when this organizing is "finished" but the big hope is that every tool will have a specific place, so I don't have to go hunting for anything.
So, yeah, this has gone a little beyond socket organizing.