popparoo and georgiana, I waxed lyrical about the the big age gap working with my sons, but I think it's only fair to post this also:
Both dh and I find the age gap can be hard on us. I've said this before on another thread, but it is, at times, a strain having a baby or under 4 yeasr old to look after for many years - in our case it will be 10 years or so before we have no preschoolers or under in the home.
We have no extended family nearby and rely on paid babysitters for evenings out. We cannot go away for a weekend alone ever. My yongest son is just too little to stay with any of our friends overnight and few would be keen on this, anyway. Sleepovers won't happen till he is five or so.
Lots of the more grown up things I want to do with my 8 year old - playing draughts, helping him with his homework, seeing a film, taking him out for meal - are near imposible to do with a toddler running around. I am not at present working, and am around lots, so if dh and I take one boy each and spend time alone with them, I still have much time to see them together. As and when I am back at work, it could be a strain for me to give each boy separate time for their separate needs.
That's not to say I regret having two for a minute - ds2 keeps me young and it is fascinating to see how alike yet unalike he and his brother are, and lovely to see how they care about each other, but it can be hard work.