Well, in LDS theology, as is the case with most Christian sects, Christ came to Earth (decidedly not currently part of the Celestial Kingdom) and lived here for a while, so it would seem Christ, at least, can roam beyond a celestial sphere. The Father, also, has visited on occassion, and so it would seem that he also can roam. - The father's home, however, is in a place of celestial glory and I'm not sure that the Son of Man is yet said to have a place to rest his head, though it's not an issue I've ever heard discussed. - I've always considered that Christ currently lives near his Father, but I personally don't expect it will always necessarily be so. Someone else will have to chime in if they recall any precedent for that idea. - Something to keep in mind is that in LDS theology, the Celestial Kingdom is not necessarily a specific place, but is rather any place which has a celestial glory. Perhaps we might say, a "type" of a place, much like the concept of Zion. There is a specific place we might refer to as Zion, and the term is used for at least a couple of specific places, but more generally the term refers to any place which is in a Zion state. (A Zion state being defined as one in which the people are one even as Christ and the Father are one. John 17:21-21)