I actually went to Madagascar for a honeymoon in October 2007! It was a fun place to visit, but it completely exhausted us. We did the RN7 route by private car from Andasibe down to Tulear, then flew to Fort Dauphin for a short bit, and left the country. So we obviously didn't do the beach thing, just the chasing lemurs thing.
We stayed in some really nasty places, but also some extraordinary places (like
Jardin du Roy). I've gotta say the one thing that really wore us down was the food. After a long day, it was always a bummer to eat a crumby dinner!
Our last night in Madagascar, we stayed at
Lavasoa in Fort Dauphin. This place was a real gem. A nice (cheap!) bungalow looking right onto the ocean. And down on the beach is this little restaurant called George's where you can eat some very freshly caught fish and crabs while lounging on the sand. It's just a crazy location for a restaurant--you can only get there by foot. It was really amazing--hands down the most romantic part about our honeymoon! (especially considering there were some nights we had separate single beds in certain places)