First of all, Steve and I practice attachment parenting. While the practical working out of this differs from family to family, it is essentially recognizing the crucial importance of helping each child to form a secure bond with her parents. One way we see this at work is through nighttime parenting. Attachment parenting recognizes that our job as parents does not end at night. Children have nighttime needs as well as daytime ones and those needs are equally important.
However, moms and dads have needs, too. Moms and Dads need sleep and need time alone together. It is not easy, but it is possible to make sure everyone's needs are met.
In our family, we keep our babies nice and close until I have nightweaned them (at about a year old) and they are sleeping through the night reliably (12-18 months?). After that, they are moved in with a sibling, but they still continue to 'visit' us now and then -- sometimes a lot of 'now and then'! If we have no current baby in with us and the child is still little (say, under two or so), they are free to just climb into our big bed. Otherwise, they can visit the quilt basket:
This basket stays under my dresser and contains two quilts and one waterproof, flannel-topped pad. If the child has any possibility of wetting at night and isn't in diapers, they/we put down the pad. Then, they can grab a quilt and rest securely beside our bed. The philosophy behind this arrangement is that it meets our children's need for security (to be comforted by Mom and Dad's presence) without making it too comfy and encouraging them to visit when they aren't legitimately scared. Sure, they'd love to sleep with us all the time, but they have each other. :)
(Just for interest's sake, the two quilts are large 'crib-sized'. One was made by a friend of mine for my older son when he was born and the other one, I made myself! It is the only quilt I ever did and it is from the book, Bend the Rules Sewing by Amy Karol.)
What about your family? How do you handle nighttime visitors?