Lucky you! Madagascar is in my top 5 places I want to visit. Did you see any racial difference between the people you saw in Antananarivo and in Diego Suarez?
Yes, dramatic. The people in Antananarivo were basically very dark Malays. Presumably they are mixed, but they are quite asian looking. The people in Diego Saurez were completely African looking. Fairly hot girls in both locales, but Diego was probably better.
Traveling in Madagascar is different than traveling in Asia in that there are fewer tourists and almost no middle class, which tends to eliminate lower-midrange hotels. For example in Thailand you can stay in very decent places where working and middle class Thais stay for about $4-15. In very poor countries like Madagascar there are really only the more upmarket accomodations that serve the well heeled (typically French) tourist and the Malagasy elite - I paid most nights about $30-80.
Food is similarly a bit more expensive, though very delicious and a good value. I think if you go to Nosy Be however there may be cheaper guesthouses as it is a bigger tourist destination. Do you speak French, kireev?