Worrying in advance really. We've just come back from center parks on the continent and saw the little gang of kids having fun on their activities every day.
Our older kids were always off like a shot to anything like that, but there were 4 of them so they always had someone else to go with.
DD2 is likely to be an "only" as she grows up (15-21 year gap between her and the others). Obviously it depends on personality so she might be the sort that thrives on new challenges, but I've got visions of her always wanting to hang around with us and miss out on the fun (plus we won't get a break either )
Can anyone with an only reassure me that their child loves to go off and play with strangers? [hopeful emoticon]