Fringed with sandy beaches and rocky inlets, the main island of Zanzibar (Unguja) is about 97km (60 miles) in length and no than 32km (20 miles) wide, making it a very manageable size to explore. UNESCO-protected Stone Town, the capital, will be your point of entry; with any beach on the main island 45 to 90 minutes from the airport, you can choose to head straight to your beach lodgings from the airport (or sea port, if you have arrived by ferry). However, if you have an interest in the history of the island or simply want to shop for souvenirs, set aside a day or two to soak up the atmosphere of Stone Town, preferably after your safari (when a bit of history and culture wouldn't be remiss) and before your beach sojourn (after which you are likely to be blissed out by gorgeous horizons and find Stone Town's labyrinthine streets claustrophobic and dirty). Alternatively, visit Stone Town as a half-day trip from your beach resort, unless you've opted to stay on the nearby island of Pemba, in which case you will need to schedule a night in Stone Town.
With regard to choosing your beach location, most settle into one resort and stay there for the duration. However, if you are here for more than a week, consider combining a stay in either the south or the east with a few days in the north. When choosing where you wish to settle, bear in mind that the south has the least-developed coastline (other than the west, where there are very few beaches) and offers proximity to Jozani, the last remaining indigenous forest on Zanzibar, as well as the best opportunity to swim with the bottlenose and humpback dolphins of Kizimkazi. The east coast has what is generally considered to be the most beautiful beaches on the island, lined with palm trees and a string of sprawling resorts and more intimate, rustic-style boutique choices. The north coast has its fair share of beautiful coastline concentrated around cosmopolitan Nungwi, which has two intimate and exclusive resorts, as well as a string of budget accommodation choices and backpacker-type travelers providing color and bustle to the beaches. Aside from the northeast, Nungwi is closest to Mnemba Atoll, generally considered the best diving and snorkeling area in Zanzibar, for which the Mnemba Island Lodge is, of course, the most ideally positioned, with Matemwe Bungalows the second choice.