We're expecting 2nd one in October and dd is 2.5 years now and still sleeping in her crib. It's a convertible crib but we plan to keep that crib for the newborn. We plan to move her down to the basement into one of the empty bedrooms ( used to be a guest room) that already have a queen size bed with a box in there. I've read about transitioning toddler from crib to twin bed, how about a queen size bed ? It seems awfully large for a toddler and if we were to transition her to queen, we plan to pull the mattress down and put it on the floor to keep her safe, unless there is a guard rail that can keep her safe. Or should we get a twin mattress for her instead ? What would you do ? TIA.