Tortola is the capitol and the largest of the British Virgin Islands. It's a pretty and mountainous island with friendly people, good food, and worthy beaches. Most importantly, it's the central hub of the BVI; It has the BVI's main airport, serves as central station for all the region's ferries, and is the charter and sailing hub.
It also has 200+ vacation rentals, most of which are quite affordable. Many of them are high up in the hills, even as high as 1000 feet above sea level. And they have magnificent views of the Drake Channel, of Jost Van Dyke, Virgin Gorda and all the other BVI islands. [more about Tortola]