I think [name]Arden[/name] suits a girl well. It reminds me very much of the name [name]Carmen[/name] which has been a long time favorite of mine.
I did think of it as boy’s name for long time because the first time I ever heard it was on a male character in the V.C. Andrews book “My Sweet [name]Audrina[/name]” which I read back in junior high. I only ever started seeing it as name a few years ago (almost exclusively in girl-name posts like this.)
It really grew on me as a girl name and while I still like it for both, I just slightly prefer it for a girl.
I think most people see it as a surname-name, and while I do usually prefer those types of names for boys I don’t think surname = boys name and can suit a girl just as easily (unless it actually mean “son of…,” I hate that)
By the by, did realize how close [name]Arden[/name] [name]Rose[/name] is to Garden [name]Rose[/name]? On one hand it’s sweet little built it pet name, but it’s too cutesy for me.
As for [name]Miriam[/name], I never really cared for the name though [name]Miri[/name] is a cute nickname and [name]Miriam[/name] [name]Rose[/name] as this very elegant ring I absolutely love, which reminds me [name]Arden[/name] doesn’t have any nicknames does it (that’s a negative for me)
All in all, I’d actually vote [name]Miriam[/name], but think [name]Arden[/name] is lovely too and you should go for it if that’s the one you truly love.