Apart from its historic connections (many experts identify it with the Ithaca of Odysseus of Homeric fame), Ithaca is undeniably a beautiful island and many cruisers favorite among the Ionian islands. See History of Ithaca for further details.
Consisting of two separate landmasses joined by a narrow isthmus, there are three harbours suitable for yachts, Vathi, which lies at the head of a large gulf in the centre of the islands E coast, and the smaller harbours of Kioni and Frikes on the NE coast. All offer shelter from the prevailing NW winds - although Vathi can be uncomfortable if on the main quay - but the latter two harbours are very uncomfortable and potentially even dangerous in strong SE or E winds. In addition, there are a number of anchorages around the island that are usable in appropriate weather conditions. More information on http://www.cruiserswiki.org the best source when you charter a sailboat in Ionian islands.