Small: 1- 1 1/2 feet or less in diameter and less than 1 foot tall Parsley, Chives, Cilantro, Fernleaf Dill (other dills grow to 3' tall), Cuban Basil, Thyme
Medium: 2 feet to 4 feet wide, less than 2 feet tall Marjoram, Basils (except African Blue), Tarragon, Savory, Thyme, Chocolate Mint and Peppermint
Short but Large: 4-6 feet wide, less than 1 foot tall Oregano, Spearmint, Orange Mint
Large: 4-6 feet wide and tall African Blue Basil, Rosemary, Lavenders, Sages, Lemon Verbena, Pineapple Sage
Sweet Bay Laurel (This is actually a tree but it makes a great central point of interest to your herb garden (whether potted or planted in the ground). It grows very slowly but will eventually reach 15-20 feet tall.)
There are very many herb varieties. Each herb is unique. Each one has been created for a purpose. There are many useful herbs that I have not mentioned, like parsley. It is rich in iron. A sprig of parsley everyday contributes to a healthy body.
The list just goes on and on. There is thus lots of scope for you to be creative when you design a herb garden.
Pink Pink herbs include; perennial basil, wooly sage, wild rose geraniums (the wild ones are pinks and purples), roses (wild garlic does well under roses as an insect repellent), bergamot, bressingham thyme.
Yellow Yellow herbs include; golden celery, golden creeping oreganum, tansy, rue, Jerusalem Artichoke, and golden feverdew.
White Herbs in this category are, elderberry, angelica, chervil, yarrow, garlic chives, chamomile, white thyme, and pyrethrum (insect repellent).
Red Herbs with red flowers include roses, bergamot, nasturtiums, poppies and pineapple sage.
Green Thymes and mints provide striking green foliage.