It all depends on how you work. If you're the sole user of the benches then make them to suit you. Do you remember using a workbench somewhere that was just right? Maybe at an old job or a friend's place....drop by to say hello and bring along your tape measure.
Let me tell you about the benches in my shop...
One is chest height and only 16" deep. It holds a couple bench grinders, a small drill press and gets used for handwork on small stuff when I don't feel like stooping or using a chair. On account of it being so tall and narrow, it's anchored to the wall to steady it. The bench is so high that I wouldn't want it any deeper than it is; working or lifting something heavy at that height AND far from the body would be too strenuous over the course of a day.
I have another, shorter bench that is 96" long and 48" deep that usually lives against a wall. That back 24" collects junk most of the time but when I work on something larger, like railings, I pull it into the middle of the bay and get at it from all sides; it beats working off the floor.
I have a couple of 48" square welding tables that see the most action. They're easy to move around and where they're put depends on what's going on in the shop.
A few general thoughts:
When I make a wood bench that only sees light use, I don't bother making the whole bench top super skookum. I'll only re-enforce the foot of bench nearest the worker; nobody bangs on the backside of a bench.
If you want a vise on the bench in a spot that isn't right over a leg then make a leg to install under the vise.
Years ago, I had a small work table that was tall enough that I had the work close-up like with a watchmaker's bench except I was standing...That was one tall table but very comfortable for light work.
An accessory I've had on benches at home was a small vee shaped notch cut out of the bench top so I could use a coping saw and provide better support for the work than just hanging it over the edge.
Want something heavy? A piece of steel plate with pipe legs welded on is quick to make and doesn't generally move around. With a simple table like this don't go with less than 3/4" plate and 6" pipe. I've used a few over the years and loved them all...but never owned one of my own. The only problem is you need a forklift or crane to move them around.
