Nice work bench Steve, we added steel drawers to our workbench, simple to build, we just had a steel shop bend up the drawer, then welded in the front and back, welded a short angle iron to the front for a pull, then used angle irons welded to the bench to use as drawer slides, done this same thing for my service truck. Below the drawers we added steel sheets to have a shelf to lay larger things on as well, we move them around the shop with a skid steer and pallet fork when we need to, otherwise they are set near a wall.
The last smaller more portable work benches we made out of angle iron, then bolted the steel top on, in case later we decided the make them longer, that way we change out the top and use the old top for plate steel on whatever project comes along, it also makes it nice to just flip the top over and have a new smooth side to work with again, mainly the table we use for welding, then once its cut or splattered up too much, we just unbolt the top and put a new sheet back on. I've used 1/4 inch for most tops.
The absolute ideal workbench I've ever seen was about 30 years ago now, the Railroad had a plate welded up and cut square out of railroad rails turned upside down, welded side by side, it was 10-12 foot square and set up on wooden ties cribbed up. The railroad was done with it and gave it to the farmer who's land they were using to park stuff on when they were working in the area, they even delivered it to him, set it up on a slab of cement he had behind his house, then he built a shed next to it, then put a lean over the plate and made himself a shop in the lean. The last I saw it was 20 years ago, when he farm was sold, have no idea if its still there or whatever happened to it, but thought I'd mention it as an oddity more than a practical workbench, as they say, you can go overkill on a workbench.