General rule of thumb is 35 lumens per sq/ft. But there are several variables that can effect this...will you have under cabinet lighting? I have a layout similar to yours (not sure the exact size of yours but it looks very close)....I have hood lighting, under cabinet lighting, above cabinet lighting, and two pendants over my island. I did one 4" above my sink (was a 6" pre-remodel and wish I would've stayed with that for more light) and then I did three 6" centered on the aisle (evenly spaced out) on the side behind the island stools and two 6" on the sink side aisle (even with the two end ones of the other aisle but no center one because it would be too close to the sink light). The two on the sink side aisle are not centered over the aisle because that would cast a shadow over the counter when you're working at it. I don't remember exactly how far they are from the cabinets but there is a general rule of thumb for that too...something like 28-30" or so. What is on your other wall, opposite the sink?