We've only recently put away the single camp bed that we had in DD3's room - her sleep has been shocking and so one of us has been sleeping on it every night. If I actually already had a queen bed, no way that would not have been in her nursery. Comfort when you're already battling sleep deprivation is heavenly.

FWIW, DDs 1 and 2 sleep in queen size beds. They used to share one but now have their own, with "sleep overs" sharing on the weekend. Its so great being able to get a seriously good night's sleep if you end up snuggled up with your LO. One of my big girls is great to sleep with - quiet, still and snuggly. The other is an absolute nightmare and there is no way I could sleep with her in anything less than a queen. If you've got the space, use the queen.