May is for warblers

Let's be honest. While there's always hope for a quality rarity, the reason that May is more anticipated than November (where honestly there's even greater chances of something really interesting) is warblers migrating through.

Black-throated Blue is a favorite of many...

Black-and-white probably isn't on many people's top 5 favorites, but they are fairly unique in their preference for trunks and large branches.

I've generally found Orange-crowned slightly more common in fall, but do usually encounter it in the spring.
Yeah, yeah, technically this isn't a warbler (in fact vireos are thought to be more closely related to crows than warblers), but Blue-headed Vireo is one of the more boldly patterned vireos.

Last, and least, the Redstart. They tend to become the dominant species as the migration is winding down. They're handy when you're trying to figure out a song though. Just call it a redstart, if you stand there long enough, you'll probably even see one...