I agree with mumofteen, if she wants the big bed let her sleep there as she is probably ready for the transition. Just buy a bed rail or put a mattress on the floor beside the bed in case she falls out.

thank you for your confirmation of my thoughts. As she is very communicative, and has expressed herself very eloquently for a toddler, I have gone with her suggestion of a proper bed. When the time comes, I hope she is just as eager to start potty training..
thank you again.