Sidney on a boy is pretty awesome, especially with the nn
Sid. I have always liked
Sidney Luke. I think your boy sibset is pushing it, though. It makes it seem like you're just being a contrarian. That said, I do like all those names for boys. And
Eartha I adore, but it seems like
Eartha Kitt "owns" the name. Not that I don't love
Eartha Kitt. It would just seems like anyone using that name would be copying/directly paying homage to her.