Arden Isabel is mine! Because Isabelle is my top choice for a girl. :)
Honestly, Arden and Mabel aren't something that I would use, personally, but I like the natural, sort of ambiguous appeal of Arden, and I like the feminine, classic Isabel with it. I think Ari could be a cute nn for Arden, as well, if you want one.
Arden Rose and Arden Isabel. I really like Arden!!! I would love it if my name was Arden...and I actually know of 3 even though I consider it very unique. I would not like my name to be Mabel at all. It just sounds elderly and frumpy to me, but I've seen it get lots of love around here (along with other ones I consider in this category such as Imogen). I'd go with Arden all the way! ;)