Benefits, rights, and privileges of marriage?

[fragment]

Originally Posted by LadyShea

I am mostly interested in why the government is involved in marriage at all. People should be able to choose to marry if they want, but it shouldn't, IMO convey rights.

Does the government directly convey rights upon the married, or is it merely recognising the existence of a relationship between people and that certain things follow from that, e.g. the right to be recognised as next of kin? An analogy might be parenthood, which is legally recognised in a number of ways, but not something which is directly conferred upon people by the state.