I know what you mean about working with the last name!
Esther would sound pretty snazzy with my last name, but less so with my boyfriends - his ends with "-der" so its almost got the rhyme-y thing going on, you know?
I'm also not too keen to get matching sibsets, per se, but I just like the harmony of siblings with names who share a similar kind of...origin, I suppose :-) Gosh, I don't even know what I mean, I sound like a cult leader or something!
That being said, I really like
Natalie,
Abigail,
Mariah,
Miranda,
Lily and
Marisa for girls, and
Daniel,
Thaddeus and
Theodore for boys.
Esther,
Lily and
Thaddeus sound great together!