Cuba - what's the latest?
My two favorite paladares in Havana are: La Esperanza in Miramar and La Guarida in Centro Habana. La Esperanza is in an absolutely gorgeous home and the food is superb. La Guarida is housed in the apartment building where Fresa y Chocolate was filmed. Both are excellent, and you should make reservations.
I was in Havana about 5 years ago, tagging along with an American choral group that had a cultural exchange visa, and coincidentally during the big Cuban music expo/festival, Cubadisco. I SO loved it.
Perhaps you already know that paladars, small restaurant in private homes, serve the best food. When I was in Havana no restaurant meal equalled the food I had at a paladar. Usually, the way to find them is for them to find you: touts will take you there. I'm not sure if there's a way to scope out different paladars, but the one I ended up at was quite good.
The food at the famous La Bodeguita del Medio isn't bad (though you'll get much better Cuban food in the U.S.); it's a fun, historical place with a nice trio playing sones. It's a tourist thing to do, but I'd recommend it. I know Cuban music well, so the trio played several of my requests, and even made reference to "nuestro amigo de Nueva York" in one of the songs.