Among my daughter and her friends "co-sleeping" seems to be all the rage. I can understand that having a new-born close by is useful especially if you are breast feeding (though doesn't all the research show that it isn't safe to have a tiny baby in bed with adults?)
But as they get older surely there is no need for a child to sleep anywhere but their own bed? I can't understand why a happily married couple would want a small child in bed with them and surely it's a dangerous precedent to be setting? I love my DGD with all my heart but find having her to stay exhausting when she refuses to sleep anywhere but with me (a real wriggler) - and it's not just about being in a 'strange' bed as the same thing happens when I stay with them.
I think having the cot in the parents' bedroom is the perfect compromise, and it used to be the most logical solution, you can see and hear the child (and vice versa) while still having your bed to yourself. We then had the strict rules of putting a baby in his/her own room from the very beginning, followed by the opposite fashion of sharing a bed with the kids. Still I'm all for just do what suits you best!
Hard and fast rules are not helpful as they don't take account of need! Some kids need the closeness that co-sleeping provides,others are perfectly content in their own cots/beds. My DGS does not co-sleep and never has..but his mum , my DD1 did! My DGD1 did co-sleep sometimes but now 6 she does not (unless unwell) need to. DGD2 still sometimes co-sleeps at 3 but it is reducing! her mum, my DD2, was always in our bed..and either me or her dad went to hers! We are all happy and healthy and enjoy being around each other..so no harm done!