I live in central/eastern NC and do not have a good track record
keeping perennials growing in a partial to full sun setting. Soil at
ground level is mostly clay.

Specifically, we built a raised bed of about 1 foot in a bed located
between our sidewalk and house (about 4 feet wide by 20 feet long).
After we built our wall using large decorative concrete blocks, we
filled it with topsoil, put a weed block material over the dirt, and
finished it with 1 - 2 inches of cedar. Planted many different kinds
of flowers according to instructions on flower pots. Most of the
plants either died or did not come back.

I suspect the issue is that I didn't provide any method of drainage.
I've used a little permasoft (I think that's what it's called - a
small, light, rock-like substance) mixed into the soil around some of
the plants, but it didn't seem to help. Now, we're getting ready to
build another bed on the other side of the house, though it'll be
around twice as long and half of it on a pretty good side to side
slope. The new bed has an existing French drain running along just
underneath the ground from a downspout. I'd like to get it right this
time.

Sorry for the long background. Here's my plan. Please let me know what
I need to do differently.
1. Dig up the existing bed
2. Add 2-3 inches of gravel in both beds
3. Lay a couple French drain channels between the rocks
4. Top with 1/2 to 1 inch of sand
5. Top with top soil
6. Top with weed block
7. Top with cedar.

Will the gravel, drains and sand solve my problem? Computers I can do;
plants just make me scratch my head! Thank you!!