I think the 'best' age gap is different for everyone
IF we go ahead and TTC this year, there will be at least a 3.5yr age gap between Aidyn and #2. I am happy with that because I know I would not have coped too well if Aidyn had been any younger when having a second baby. However I certainly admire the parents that manage fine with having their kids very close together.
I really wouldnt want there to be much more than 4 years between my two kids though, so I will have to make a decision very soon in that case!

We are hoping to have #2 ASAP. DH made the interesting point about people wanting to spend time with the 1st and giving that as a reason to delay having a 2nd. In his view that means that you are kind of accepting that every kid but the 1st somehow will "miss out", because after #1 there will always be competition (he is the 2nd of 4, BTW)
Interesting point Rory, however in my case, if you are only planning on having 2, then #2 wont miss out as much, because there will be no newborn/infant #3, which is what takes up a lot of time and energy...
And I think by waiting longer (until #1 is older) to have #2 ensures that #2 will be able to recieve a bit more attention than I would be able to give if #1 was still quite young as well?
Did that make sense LOL?