This floor plan features a freestanding workstation in the center of the kitchen.
Either the sink or cooktop works well as the island workstation.
In a U-shape layout, leave at least 10 feet between the legs of the U (cabinet front to cabinet front); that will allow for a 3-foot-wide island with adequate walking space around it. Don't install an island in a U-shape kitchen if two workstations are on opposite walls.
In an L-shape kitchen, allow at least 42 inches of walking space on all sides of the island; in a two-cook kitchen, 48 inches is best.
In a large kitchen, the island is a convenient location for task-specific countertops, such as butcher block for chopping vegetables or marble for rolling out pastry dough. In a small kitchen, consider a portable island such as a rolling cart or table. It won't accommodate a bona-fide workstation but will give you extra counter space where you need it.
If the island also includes an eating counter, keep it well away from the cooktop.