Mae Haad is the island's main town and ferry pier — the first thing most visitors see as they step off the boat. The streets closest to the pier are lined with the businesses you would expect: ATMs, motorbike rental, pharmacies, tour operators, and restaurants aimed at the newly arrived. It is functional rather than charming, but the convenience makes it a reasonable base.
Away from the pier, Mae Haad has a more genuinely Thai character than Sairee Beach. There are a couple of good local restaurants serving proper Thai food at local prices, a small market, and a slightly slower pace. For exploring the rest of the island, Mae Haad is a good starting point: it is centrally located, the road to Sairee heads north and the road to Chalok Ban Kao goes south.