I know sisters named
Sullivan and Sutton (sorry to make you gag, lol...I feel the same way) so they're who I immediately thought of when I saw the title to your post. But I even though I don't love
Sullivan, I'd much rather see it on a boy, of course.
Silvester reminds me of
Sylvester, and therefore the cartoon cat and Mr. Stallone. Not quite usable, imo. I like
Dominick, though I prefer it without the "k" but I don't think the "k" is horrible by any means. But
Dominic seems to be getting more popular here in the U.S. :-/