Nice! My honeymoon was South Africa>Mozambique>Tanzania>Zanzibar had a blast!
Couple of tips:
- Watch out for scammers - I was duped into giving money to a guy for flights and he never booked them. That said, you can book a lot on the ground there, I think our Safari of NgoroNgoro and the area was only a couple of hundred bucks vs thousands when booked here.
- Have some cash available for bribes on border crossings - speeds things up- but be careful if that is a new concept to you and don't do anything that makes you uncomfortable.
Highly recommend Pemba if you dive, and Zanzibar even if you don't.
Watch out for crossing into YellowFever zones - or get all your innoculations first... Some African countries (SA for example) will let you in without having your shots, but if you cross into Moz/others and exit home via SA then they will bust your balls and might want to make you have all the shots at the airport there.
Oh, and don't bring money back with you - I found it impossible to change back some money out of country (Shillings I believe from Tanzania) likewise, you will be screwed over on exchange rates at border crossings - so try to find the right balance there.