OK. I've been watching the sun more. Mostly morning sun in dappled/minimum quantity for most of the area. The north-eastern edge gets the most direct sunlight in the afternoon, but not harsh sun and only for a couple hours.
So I've played with my layout to better work within those parameters. I think this is the one I like best.
At the bottom is the bench (24 inches deep). My idea is to put trailing plants in the top and middle flower beds along the bench, and also along the stretch of the top bed that is behind the bottom bed. That will soften the look of the cinder blocks in those spots. The rest will be mostly behind non-trailing plants so won't show. The cinder blocks are standard 8x8x16 (actual measurements 7.75 x 7.75 x 15.5) - I've mapped it out so I will be using full blocks only. For the bench, the bottom bed's front edge will be under the back of the bench as a support. The partial blocks showing will finish under the bench and I will add additional blocks as needed for stability, etc.
I'd like to try growing cucumbers in the bottom tier along with dill (so I can make the family recipe pickles). Of course, I won't be doing any planting until next spring - have to build it, fill it with dirt, and watch the moisture levels over winter first (might need to create drainage holes at the bottom).
Thoughts? Ideas?
