Weighing in on the kids in bed...as it's been mentioned, every situation is different, and there is no magic answer.
But with us (kids are older now), I found that sometimes they really were scared or had a reason to be in our bed, and other times they seemed to just take advantage of the fact that "they could". It then becomes a routine, and just normal practice if you let it get that far.
We kinda put our foot down, and said enough is enough. New rule - everyone sleeps in there own bed. If you need anything, and it better be a legit reason, then come on in and tell
mommy or daddy,

but if you just want to come in, NO!. You have your own bed, and it is in your room.
Every Night we would tuck them in, give them a kiss good night, and tell them we love them. But they had to stay in their own beds.
We also found if we let them sleep with an extra stuffed toy (or a few extra) they'd be happy.
Seemed to work, but we never really let it get to a point where they were SO used to coming over.
On a side note: we have friends of the family, and the mother let her son sleep in their bed as a baby... and he NEVER left... he is about 15 now, and still sleeping in mom's room. Dad NEVER sleeps in that room anymore.