I just finished answering to a post of casa particulares and had a flash that what could help a traveller to Cuba more than a list of recommended casa particulares in Cuba?
I'll start with the one I stayed at in Havana. It's website is http://www.geocities.com/aniaramirez/Home.htm
I stayed in this casa for 3 months and I cannot recommend it enough. The woman who rents out used to be a Spanish teacher at the University of Havana and even ended up giving me Spanish classes so I left speaking practically fluent Spanish. The room is wonderful and the family included me in their everyday life so I didn't feel like an outsider. Still, I had a big door I could close and have my privacy which was respected. The room has a balcony onto the street and it's not just because I'm fanatic for balaconies but also because it was just a wonderful spot to sit and watch life go by that gave the room a special atmosphere.