I had the joy of visiting Sultan Sands and Blue Bay Resort with my wife and colleagues from East and Central Africa in February. The rooms were great and the staff very helpful in organizing our conference facility.
The buffet menu was only fair, but the beach side restaurant was better than most hotels I've been at in the region.
The highlight was a snorkeling trip around a nearby island. Simply the most spectacular snorkeling I've ever experienced.
Great value option for a visit to Zanzibar!