I'm going to be the lone dissenter. Your space seems very nice, warm, comfortable and casual to me. The first fixture has a dressier feel to it than the room does. The second option down feels very heavy visually to me and since it's directly over your dark island top, I'd avoid that one. The bottom of your pendants will come 30-40" from your countertop. So as long as you have your fixture hit at that level, you're fine. That gives you roughly 22"ish inches to play with for the height of your pendant. And your length of your island is a good length to work with. I like the fourth option down. I'd put two those lanterns over the island or two of the other smaller PB pendants. I think they're both nice and casual and pretty and keep the warm feel of the space. I could see something like 3 working if the scale was right. But I'm not sure with the 8' ceilings. But I want it to have more than 3 lights on top yet not as many as 5 does. I've seen quite a few online with those same lines.

Hiii 36 inches is perfect! That gives more than enough room, seeing that the shades are each 12 inches. You don't want them too close, nor too far. 36 inches is great space. Best regards, Janaé

What's the rest of your lighting plan like? Recessed ceiling lights? I'm asking if the pendant lights are needed for the function of your island, or whether they are going to be there to make more of a visual statement. check out How to Light a Kitchen Island from YLighting Their products are all very modern, but just read for the principles.

yes your math is good those fixture will not give good working light, too bright will be right in your eyes, to dull will not light the surface, be sure you have good placement on the recessed.