My sons are not circ'd. When I was pregnant with DS1 it seemed like such a big issue. I felt that it should be my husbands decision, since he was the one with a penis. However, now that I know more, and as soon as my son was born, I knew that was a crap reason, and it was really an easy decision: of course I wouldn't cut off part of my perfect son's body. Who cares if DH has a penis or not, it's not his penis to make the decision about! Luckily DH, who is circ'd, had a best friend who wasn't, and so didn't think it was weird at all. He was completely supportive of leaving our babies intact.
As far as convincing others, and judgemental relatives, I've found that people don't really discuss genitalia. They may say one or two snide remarks, but it's not really dinner table conversation. I agree with others that it should just not be up for argument without thorough research on both sides. "He won't look like me" just isn't a valid reason. He may have dark hair, and daddy is blonde. He may be shorter or taller than daddy. Why does a difference in a penis mean we should cut something off him, but we aren't running out to die our baby's hair or binding their feet to make sure their shoes are the same size. Of course our children won't look exactly like daddy: penis included.
I'm not Jewish, but circumcision seems very prevalent among my conservative Christian religion. I have been reading a lot in the New Testament about it, and I really feel that even if that is an issue, there are lots of scriptures to support NOT circing. If anyone wants me to look them up again, I can do that.
Many parents feel like circing is a personal decision, and I totally agree, but I think it should be the personal decision of the child, not the parents. I'm not sure it I know very many intact men who would even consider circumcision when they are adults, so why would we do it without their consent when they are young?