Charlotte will be 3 1/4 when this one is born... (So 2.5 when we conceived.)
I like the idea of this gap - Charlotte is old enough to know what is going on, is excited about the baby, old enough that she is already weaned (a few months ago!) and is quite happy so far to understand that the boobs will be for the baby now...She is non stop talking about the baby, to everyone! lol

She is also starting school next year (Montessori starts at 3) so I will also get the time to spend with the newborn one on one which I am so thankful for.

Like feeb says though, I think everyone is different like that... I didn't want a huge gap, so any more than 4 years and I would have been not too happy about it, but I also had no desire to have more than one in nappies at a time, Charlotte is long toilet trained, bed time organised and all that 'hard' baby stuff is over with, so I am free to focus on the new one without distractions itms.

Good luck TTC!!