originally I had mine isolated, but then I moved it to old villager's spot facing the southern shore. it is near a resident's house, but it doesn't look too bad.
I like it isolated and near the cliff. I have my lighthouse and windmill at opposite sides of the vertical ramp leading to my beach which I think looks really nice. It's a great view from the dock except for the basket where you pick up items.
I agree that the lighthouse looks best when it is placed near a cliffside, though whether or not it is isolated isn't an issue to me.
If the color doesn't suit your town very well, as was my situation, it can help to surround it with alternating matching and contrasting flowers to make it transition more naturally into the rest of the town.
I don't really mind if the lighthouse is near a villagers house, but I feel that it always has to be near the cliff so that's always where it ends up for me.
I wouldn?t mind if the light house is placed near a villager, it would be just like a small cosy village where everything is close together. However it needs to be build near the cliff overlooking the beach^^