I think a very good and simple poet in spanish is Nicanor Parra. He is chilean as Neruda, but his style is completely different. He is the founder of the "anti-poetry".

Here you are a link to one of the best Spanish poetries of the XX Century. Miguel Hernández. http://www.poesi.as/Miguel_Hernandez.htm

For me, one of the spanish best poets is Ángel González. http://amediavoz.com/gonzalez.htm

He is a great poet , I am a fan of his poems too. Matilde, years or days sleeping, feverish, here or there, gazing off, twisting my spine, bleeding true blood, perhaps I awaken or am lost, sleeping: hospital beds, foreign windows, white uniforms of the silent walkers, the clumsiness of feet. And then, these journeys and my sea of renewal: your head on the pillow, your hands floating in the light, in my light, over my earth. It was beautiful to live when you lived! The world is bluer and of the earth at night, when I sleep enormous, within your small hands

I would suggest that you also explore female writers. My favorites: Alfonsina Storni, Juana de Ybarbourou, Gabriela Mistral and Delmira Augustini.