'It all depends...'

What colour brick is providing the background to the planting?

Did you want shrubs and perennials or annuals? How wide is the bed?

Have you got a microclimate there that actually gives you a local higher zone (an 8 instead of a 7)?

Did you want to use the walls for espalier work?

What sort of soil - and are you able to water over summer - or do you need to take water restrictions into account?

What colours appeal to you? And do you like dramatic combinations, or gentle, cottagey plants? Is scent an important consideration?

Do you garden 'often' - or just sometimes when there's a gap in the busy-ness? ('cos it wouldn't be kind to mention plants that would maybe take more time than you have available.)

Salvias, daylilies, gazanias, dianthus, sedums, petunias, marigolds, agapanthus, crocosmia, ornamental grasses, amaranths, coleus... All sorts.

Try reposting on the 'New to Gardening' or one of the 'regional' forums for heaps more ideas. A garden bed such as you've described has lots of potential for great combinations.

Agastaches are tough plants that would look great in front of your brick wall. Especially Agastache 'Apricot Sprite' which is a dwarf orange flowering perennial with silvery leaves. The ones I planted this year were nice and tidy and bloomed all summer and are still blooming now! Dianthus, Penstemons, Sedge Grasses,Gaillardia, and Bugbanes(Acatea) are all tough perennial plants that do extremely well in full sun hot areas. Also, these plants all would look great in front of your bricks. Some of these plants can be hard to come by in most nurseries. I always shop online for the majority of these plants, and have had good luck this year with Streambank Gardens, and Dutch Gardens. Have fun with your garden.