Best age between children
I don't have any scientific basis whatsoever, so I don't know the actual 'best" age between kids. I imagine this changes depending on what characteristics you're trying to enforce. My husband and I have decided to attempt to have our children pretty close together though, as I think this will help with sibling bonding and so we will also have time as we get older to enjoy things as a couple. I have always wanted a close family. Whether or not this works, only time will tell.
As for us.. we still need to get through #1.. ha! But we have chatted the other way around.. perhaps 4-5 years between.. so we keep some sense of sanity and not 94854 toddlers at one time in the house.. ha! Plus my brother and I are super super close and 4 years apart.. I kind of like it :)