So here are some more bench ideas.

First up is this tiny torsion box top.  It does not need the holes in the side, but it shows that you don't have to go overboard on this to make a strong top with little material.

Next we have this old English style workbench that is made entirely from construction lumber.  I'm not a big fan of the wide face or the tool groove in the back but it is nice to know you can make something fairly complicated with relatively inexpensive materials.

The best part of this build is this mortise and tenon support system under the table top.  They call it a torsion box here but it is not because it lacks a bottom span of wood to create the torsion.  I don't know that you need to mortise the wood, running screws into the ends of the cross pieces would be fine for a workbench.

Finally we have this worktable made from a solid core door and some 2x4's.  I like the idea of a prebuilt top that is flat and solid for relatively little cost.  However solid core doors come in fixed sizes and they are not easy to cut down.  And right now new doors are crazy expensive, so I would need to look at a reclaimed material lot to find a cheap enough door to justify this.

I also really like the fact that the whole table is up on rollers and has a very open bottom area.  I'm suspicious about the storage cubbies, I suspect they would be cluttered up in no time and adding drawers would be a better use of the space, but I would need to think on that. Maybe a compromise with a bit of storage and some drawers would be perfect.

Here is a picture of my original shelves, before they got cluttered up.

And my current workbench with the side up.

And the side down.  You can see there is not much usable space on the wall because of the door.  I could possibly put in one small cabinet over the worktable but the pegboard is probably the better use of space.  I could go with open shelves, and I may actually cut my pegboard down a bit and add in at least one more shelf since I struggle to really reach anything at the top of the board. Honestly I really don't care for the pegboard, but I doubt that French cleats would be much better.  I really want something that locks in solid to the wall but has lots of spaces. for fine adjustment.

So as an initial pass my existing workbench is great but it has a few issues.  First this movable section is not really as nice as I would have hoped.  It is a bit less stable and flat as the main bench (I would not hammer on it) and more importantly it is not convenient to be folding it up and opening it back out since you have to completely clean the space up every time.  Also it makes the right edge of the table fairly useless for sawing or really any hanging of a piece of wood off of.  

The cutout in the lower shelf seemed like a good idea, and it is in fact nice when sitting at the stool, but I never sit and work on the stool and I just end up with a much too small shelf.  Finally there is no real lip on the edge of the bench so it is hard to clamp things to it.  The 2x4's are too tall and too skinny if you can get a clamp around it.  Oh, and I currently have a lot of things stored on top of the table and that turns this into a storage space rather than a workbench.

My thought is to put the bench on wheels and make it about as wide as it is now when folded up.  That way I can push it against the door but still easily roll it out when I want to work or need access to the door.  I'm torn on the bottom. I want some sort of storage down there that is more space efficient, but do I want it built into the table, or separate so it can be more easily customized (say a table saw on a rolling cart someday)