These two directors are very different, despite my tendency to mix them up, or even combine both of their names in one (it sometimes comes out as Almonabar...), but they do have two films that work together nicely.
From Almodovar, I say watch Talk to Her - Hable con ella. The colours had me hooked immediately, add to that the extremely emotive soundtrack and Pina Bausch, and the first time I watched this film, the story took a back seat. Kind of good - it's tragic and disturbing. A bullfighter and a dancer are both in a coma, and the men that care for them develop a weird friendship. It's a beautiful, memorable film.
Mar Adentro - The Sea Inside, by Amenabar, is equally tragic and disturbing (it's about what drives one man to desire to be euthanized), and equally beautiful. You feel like a bird, swooping and soaring around the stunning coastline of Galicia.
The link? They're both Spanish films, of course, and they're both good "discussion" films. They're about relationships and different facets of human nature. Technically, they're about excellent camera work. They're couch-potato transportation. Both have soundtracks that add another layer to the stories.