DD1's first name was picked long before she was conceived (DH had loved the idea of it as a girls name since his late teens lol). Her first name is actually Cassiopeia which is a really long name and so is our last name so we wanted a short name for the middle name so picked Ann.
With DS I wanted to honour my grandmother who died when I was 3 months old. Her name was Phyllis but she hated her name so I thought that if I changed the name to Phillip it still honoured her without using her name. DH wasn't keen on it as a first name so we started with Phillip as the middle name and searched for a first name that we thought worked well and ended up choosing Zachary.
With DD2 we couldn't agree on a name, DH had a list of first names he liked but I wasn't keen on any of them and I had a full name I liked but he wasn't keen on it. In the end we compromised and used one of the first names he liked, Abigail, with the middle name from the name I wanted, Jade.