We stayed in the wonderful Sevilla Hotel in Havana and then 2 Casa Particulars (people's houses) in Trinidad and then back in Havana. In retrospect I would probably have finished with the hotel as after 2 weeks in Cuba you really need a bit of luxury! The casas are great however, as you get to stay with a proper Cuban family and they love kids.
Carrie found us all the casas, and she was invaluable. Her site is www.cuba-particular.com and you can contact her at carrie@cuba-particular.com