With my DD, I bought a pottery barn kids crib bedding set which had a twin and queen quilt available as well. B/c it was not to "babyish," I have been able to move the crib out and move a regular size bed right in without painting or redocorating the room. She could probably stay with this set until she goes to college.
Looking for the same type of flexibility with this new baby's bedding, plus I may keep the twin bed in the nursery with the crib to have extra sleeping room. I've found tons of girl crib bedding that has a matching twin bedding, but no such luck with little boy or unisex bedding sets.