Another alternative is to have a custom island designed just for your needs. Kitchen design experts can help you come up with an island that will fit perfectly into your space and also have all of the components you really want to have. You can add a cooktop, a sink, or even a built-in microwave oven which can free up a lot of your counter space. Both a cooktop and a sink built into an island can help the cook become more a part of the festivities when you're entertaining if the island is used as a room divider between the kitchen and other living spaces.
Space and Design are Important : You need around 3 feet of walking space around the island unit, and you must be sure that the drawers and doors in the cabinets have room to open. If you keep to the 36 inches then you should be OK. The only dimension that must be stated is that of the counter height. Ideally it should be the same as the rest of your kitchen units. If not, then it is not a disaster, but can be disconcerting when you are working on the various surfaces at varying heights.
Pick a countertop for your island that matches your other counters or make it stand out by using a contrasting material. Also, your choice of cabinetry and decorative elements can make your island into a real quality item, similar to a fine furniture piece.
Countertop material for the island doesn't have to match the rest of your kitchen countertops as long as it is harmonious with the room's overall design. You may want to splurge on solid surfacing here, for example, and use laminate on the other countertops. A butcher-block countertop is ideal for chopping, while granite or marble works well for baking purposes and for rolling pastry dough.