There's 4.5 years between me and my sister and I can't honestly say that the age gap bothered me when I was little. There really didn't seem to be any difference between our interests - we played together heaps. We're not that close now but as someone else said, that's more down to personality rather than the age difference. I think if kids are going to get along they'll do so regardless of the age gap. If I had more of a choice in terms of timing then I'd go for a bigger age gap but maybe that's because DD is quite full-on at times.