The 3 year resonates really well with me, as I said. I love that DS was old enough to participate in the prenatal appointments with the private midwives, and understand what was going to happen at our homebirth. He was old enough to feed me nuts (that I didn't want but couldn't speak!) during labour and give me water from my bottle. He was also (and still is) breastfed, so loved sharing that with his baby sister. He has been very much a part of her life with no jealousy, and that's in large part to do with how I've integrated him given his developmental stages. He has waited patiently (and sometimes not so) for her to grow big enough to play with now, and he has experienced the joy of watching her grow.
My sister and I are 23 months apart and whilst we played together as young children, we very much weren't close from about 10 till about 22. My cousins family has 6 children, all about a year apart for the first 4, then the next 2 are about 3 years apart. The first 4 are not very close, and moaned and groaned about each other until the last 2 years - the eldest is 36! So, I don't believe that close age gap means close relationship - that is contingent on so many other things coming together!
So, for me, the 3 year gap is my minimum preference. It might not work out that way next time round if we have an accident, but I'd really like to maintain that minimum, especially living on a farm, where I just can't afford to be completely taken up with young children at similar intensities of attention-requirements. But then, I was never really the clucky type, either. I love my children and give them all I believe to be the best and do it with unconditional love...and I'm not aching to have small dependant children at my feet, either
The Gabrielle Palmer book 'The Politics of Breastfeeding' actually has some very constructive and interesting sections on fertility, age gap and number of children. I guess the things I've read have supported the previous readings that support how I want to do things. It is evolutionarily sound to spread children out, and now we live in a fast-paced modern society that has changed the social conditions, but the physiological and psychological conditions are still playing catch-ups. Big families are a sedentary-life phenomenon.
I've been called into question for 'leaving it so long', which is really rude, especially when you know they're telling you you're selfish...as if! Whatever you decide or are dealt, we still need appropriate support from family, friends and neighbours.