I don't know about polygamy in the after life. The reason I say that this is not the right place is, when i have talked about this kind of stuff before, it usually gets ugly, which it has not so far.
But a spouse, as we understand the doctrine is essential to progression, both here and in the next life. I don't know how it all works, but it seems to me that God intended his children to marry, form family units. I can gather from that that having families or being in families are an important part of existing with God after this life.