C.P. Cavafy is arguably the best-known "Greek" poet. Based in Alexandria, Egypt, Cavafy was of Greek ancestry and wrote primarily on historic and mythological events of Greece. If you like Rumi, the 13th century Sufi mystic whose poetry is enjoying a great Renaissance, I think you'll also enjoy and appreciate Cavafy.
1. Justine
This is heresy on my part, but I first discovered Cavafy's poetry in Lawrence Durrell's "Justine", a fascinating book where Cavafy is a presence in the background of Alexandria, where the story takes place. Durrell included two of his own translations, "The City" and "The God Abandons Antony". While I've appreciated other translations since, for these two poems I prefer Durrell's take on them.
2. The Canon
More scholarly, annotated approach to the 154 poems regarded as making up the "Canon" of Cavafy's work.3. Collected Poems of C.P. Cavafy
An inexpensive edition of the poems of C.P. Cavafy.