You may only have a limited space and you think that seating will only make your kitchen look crowded. However, it does not mean that you can't have seating. For a room with limited space, you can use smaller stools. To save space, you can also choose chairs that you can store in a closet when you do not need them.
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.
If you wish to have granite or marble as island top, do ensure that you have invest in a much more studier base that is capable of support the heavy weight of these material. The granite top can have box shape cuts at certain areas to include a sink, a grill and an electric stove. Below the island top one can add pipes to supply water to the sink or electricity to the appliances. The shelves can be polished or painted differently from the top to get a splendid looking kitchen isle.
Another problem you might face if you buy your kitchen island as a separate unit, and not as part of the overall kitchen, is matching it to your existing cabinets. This might not be as easy as your think, but if you purchase a solid color, such as black, white or red, then you should get away with it.