love both names!! Henry was going to be our name if it was a boy, however im having a girl, both the names Evelyn and Charlotte are on my short list, along with Clara and Ellen! Wish my husband and i could come to a decision like you!!
Personally would probably prefer Jacob Henry and Charlotte Evelyn but your choice or name order is lovely and you both agree (not always easy from what I see here - one of the few reasons I'm glad I was on my own!) so stuff anybody else!
I love both names, however, do you want Henry Holmes? really?
Shame, as Henry is a truly fine name, but personally I think that sounds not so great. He'll go through life with people calling him his name with either completely dropped "H's" ('Enry 'Olmes) or over emphasised "H's" (Hhhhenry Hhholmes), it probably wouldn't happen with any other initial letter, but H's just attract that kind of attention and diction......
And Evelyn Holmes.... all I can think of is Eamon Holmes. Bonkers I know, as it is a girl's name and everything, but that was the first thing that came into my head!
Oh, and please avoid the initials E.C. for obvious reasons, especially for a girl. My PIL has the initials R.C. and it has haunted him all his days..... he is 65 and people still call him "arsey" much to his UNamusement!