Simply stated, Emerson Spice hotel in Zanzibar is incredible.
From the moment you step in the front doors (only accessed after a hard-to-describe incredible walk through Stonetown's narrow streets) you are treated like royalty.
The rooms are stunning (see all the pics on Africa Travel Resource).
The rooftop restaurant is delicious and very reasonably priced. The breakfast (which they serve in your room if you request it) is also great.
I would advise calling them before you arrive in Zanzibar because they can arrange to have a driver meet you at the airport and bring you to the hotel for a very fair rate.
We had a driver named Abdul and he was very nice and dependable.
When you exit the airport baggage claim at Zanzibar Airport you will be bombarded with the usual requests for taxi drivers...so having someone who is already there meeting you is much better.
We also got a chance to meet Emerson, the owner/creater...and he was incredibly nice, charming, and just an all around good guy.
If you are staying in Stonetown, don't even consider staying anywhere else...we walked to all of the other hotels and were glad we were staying at Emerson (and the prices were the same).