I assume you are referring to evergreen azaleas? I know of no design plans that address azaleas specifically (and I am a landscape designer). Typically what you would look for are plants that will grow to a similar size and height but offer a variety of bloom periods to extend the show as long as possible. You could possibly include some reblooming forms (i.e. Encore azaleas) to increase the flower show into fall.

Your best method of approach is to check out area nurseries that offer a large selection and choose from those that meet your size and flowering requirements. They should be in bloom in your area now, if not a bit later, and are pretty common at this time of year.

I'd also suggest visiting some local plantings - perhaps a Japanese garden or other public botanical garden - and see what's what, although plants in these situations are not always labeled for you to refer to later.

gardengal I have no preference for deciduous versus evergreen azaleas yet. I thought the deciduous form was more native to the US and easier to grow here?

I am fine with selecting to extend bloom periods. Do you have any specific ideas? I like whites and reds, and I tend to prefer the double flower varieties more than the ones with star patterns.