Most of the more unusual and dwarf varieties of azaleas bloom in May. Browse through the azalea beds at Betty's for inspiration. Another great thing to do is to visit either the National Arboretum's great azalea collection or drive through old neighborhoods in places like Arlington and Falls Church, where you can see mature azaleas in their glory.
There is still plenty of time to plant new azaleas. Make sure to prepare the soil well, mixing in plenty of organic material such as Betty's Clay Cutter. Remember to mulch well with Betty's Double-Shredded bark mulch to moderate soil temperatures and moisture levels. Pay close attention to water needs the first year. Until they are established, azaleas require plenty of water to keep the root balls from drying out.