Sylvia, with the Y spelling, is one of my favorite names. I think it's unexpected, vintage, very feminine. A tad glamorous. Also reminds me of silver and forests, which are nice images. I also like
Silvia (I actually first liked this name in the
Silvia form) and it is more streamlined and cleaner than
Sylvia. However, right now I prefer the classic look of
Sylvia. If I met a little girl with this name I would be thrilled, and a little surprised, yes. I would use it myself.