Watching my brothers with my children is one of my favorite things in the history of all families of all time. Daniel was in from Oregon for a few days and the kids got as much time as they could with him.
One afternoon he was "roughing housing" with Ridge-newborn version. He called me in there because Ridge was entertained and smiling. When my brother has my newborn smiling, I sprint/stomp through the house to get my camera for a picture.
Uncle rough housing is good at any age.