Arthur is a favorite name for both of us. Isaac is acceptable for us both and goes well with DS's name, Xander (nn for Alexander). Middle name is after my grandfather.
I compulsively nickname, so Isaac would probably become Zack at some point (which presents a problem, actually - one of my best friend's sons is Zachary - either goes by the whole thing or Zacky.) DS goes almost exclusively by Xander. Zack and Xander seems even more matchy than Arty and Xander.
Re: Which boy's name?
Oh I really like Arthur and Isaac!
I voted for Arthur.