Hello,
Really there is a lot to do & see in Znz :-)
First and foremost accomodation: If budget then Flamingo guest house is well situated cost is circa $10 pp bb from the port a taxi should cost not more than $2-$3
Spice tour is a must ! there is a guy oppersite the port gates who is very well known Mr Mtui he is in most of the guide books.
A visit to the Jozani forest to see the Rare Red Colobus monkeys is possible on the way to the coast, what a lot of folks dont know is, a guided tour of the mahogany forest is included in the price of visiting the monkeys and is very very interesting !
Place museeum, a very romantic story to be found about a daughter of the last sultan who ran away with a German businessman, if you are ever in Hamburg you can also look for her grave as a follow up.
The gardens in front of the Palace museeum is where they have lots of little barbcue stands at night where you can try the speciality of Znz, grilled Octopus ! mmm :-)