I resumed work on the craft area work bench for the wife this morning and things have been progressing nicely. Each corner of the support frame is reinforced with a metal right angle brace. This may be over-engineering the frame, but the goal is to have this last for several years and take a lot of heavy use. My view is that it's better that the design be tougher than it needs to be.
After putting in the second long frame, I added perpendicular support struts as shown here. These are also reinforced at the corners with right angle braces.
In order to make the end supports a little more aesthetically appealing, I cut two sections of MDF board at right angles witha 45° diagonal cut. This gives much-needed structural support to the bench top while leaving a small side profile.
This support structure is anchored to the wall with 2½" screws. It's also connected to the wall brace with another 2½" screw and a right angle brace.
After installing both end supports, I affixed long boards from the support corners to the main frame body. These boards will serve to support the table top that I'll be bolting on tomorrow morning.