My 5 year old dachshund slept in the large crate with our new puppy.  We never had a crate for her.
It was obvious she loved it.  When he got so large that his "puppy play" seemed to really be tiresome for her, we purchased a small crate for her and located it in the living room, next to my chair.  We left his in the bathroom.  At night I closed the door to hers so she could not get out.
The result was not only that she would run to it daily to escape from his incessant picking at her, but, she finally was successfully, completely housetrained!  She was 3 years old when we got her, and she used to wet her bedding, which was a standard size fiberfill pillow (I assume to hide her misdeed)that I was washing nearly more times than I cared to. We got the fleece pad that fits the crate.  No more wetting her bedding!  She loves the security of it, and likes a blanket thrown over the top to make it "cave like".  She is perfectly happy and secure.