Whether to mount benches to wall or self supporting, is a good arguement, which can be debated. Mounted to the wall has the benefit of being able to sweep under it easy. Self supporting can be moved around. In one of my barn that could be used for parking vehicles, I have relized how little room there really is for opening doors. I am glad I have self supporting benches that I could move a few feet if I decided.
A great advantage of self supporting benches you have a bottom shelf. This is a great value. Hard to sweep though. Granted you can just put stuff on the floor, with the ones that are built on the wall. Though this is hard to sweep too.
One design I like now, is shelves with a real deep middle shelf, at bench height. I am thinking of doing a hinge that can lower from the shelf above it. For storing miter and table saw blades. But you could almost anything. There is sorta wasted space under a shelf built out of 2x4s.
One shelf I built for my camp I dado all 2x4s. I basically built the ends, like ladders, then dado in for the cross supports. This was nice for fast set up by myself. I was able to haul up in my truck with it flat too. The dadoing took awhile. Might be quicker to 2x4 legs two thick, leaving and opening to put the cross sections on. Though this woud add some weight. Sliding the shelf out, is already a job.
Another shelf I did I put a back plane, and put all kinds of hooks, and lots of stools. In the front of that shelf I ran to strips of wood the length of the shelf, and put a space in the middle. All my sockets are in their and wrenches hanging on back wall.
