I think Cailyn is a beautiful name. I like to spell it Kaelyn (it sounds Celtic).

It "sounds Celtic"? This name neither looks or sounds Celtic to me, and by "Celtic" I think that you mean "Irish". I know Gaelic and this name is not Gaelic, just a mangled American version of either "Cailín" ("KAH-leen")(which means "girl" in Irish Gaelic and is not truly a name) or of "Caoilín" ("KAY-leen") (which means "little thin one").

Frankly, this trend of "-yn" names is really growing old; they do not look like they will age with grace, since they belong to the young- I don't care that children grow up and then adults will bear these names, because names that end with "-yn", "-ayden", and "-ee" conjure up the image of children, of growing up with a name and an appearance that are increasingly mismatched with each passing year.