It sounds like you'd like to achieve an English garden--full and lush.
The plants you plan to put in are summer-flowering--where they'll likely all be in bloom at about the same time. If a summer garden is what you want that's fine but if you want to have this bed bloom from early spring to fall; you'll have to add other plants. This is to keep the bed interesting and attractive before and after your summer flower choices bloom.
For early spring colour, the obvious thing is to plant bulbs like crocus, hyacinths,tulips and daffodils. You can only really do this in the fall.
Some nice spring flowering perennials include pulmonaria or lungwort(short plant with speckled leaves and pink-to-blue flowers), creeping phlox groundcover, etc. When you go to a garden centre, they should help you find a variety.
There are about(at least) 7 perennials that will give you blooming colour from May to October. They are as follows: Columbine(medium to tall),Peony(med.height-large-flowered),Daylily(med.to tall-nice foliage when not blooming),Iris(large-bearded or small varieties),Phlox(tall-fragrant showy),Asters(med.to tall daisy-like fall-blooming) and Hollyhocks(very tall-back of border plant-blooms in 2nd year).
These plants are good basics for any garden bed.
You mentioned you wanted to lay your plants out in rows. This is okay but a little formal. Planting in clumps is a little more natural. In nature you don't see plants all lined up like soldiers. A good plan for you may be to place your tallest plants at the back of the bed, medium heights next moving gradually to smaller plants and groundcovers at the front.
Eighteen Black-eyed Susan plants in addition to the others is going to require a large bed. Black-eyed Susans when they mature in about three years can be as big as 3ft wide and 2 feet tall. Remember, the perennials you put in now will need much space to grow.
I think since this bed isn't dug yet you should pick up a good gardening book that details the digging and planting of a garden. It'll help you figure just how much room you have in your yard for the plants you want. Hope this helps!
