Power
We are introduced to Roman nobility when Crassus demands to-the-death gladiator matches. Batiatus who runs the training facility does not allow matches on site. But Crassus can do what he wants when he wants, and when he can't he is able to buy his way into doing so. Back in Rome the Senate has the majority of the power in the great city. The open forum meetings are more like chess matches being played by the members in order to strategically take power away from one another in order to have their ideas to lead the city. Lastly for Crassus, we see him take Varinia as his slave at the end of the film. It is a sign of him becoming dominant--or at least attempting--over Spartacus.
Freedom
The entire journey for Spartacus is about freedom. He was sold into slavery as a 13 year old boy, but has always seen himself as a free man. He believes that no man has the right to own another. We see that this is the driving force underneath Spartacus' dream. Throughout the film we see the slaves pursuing their freedom at any cost. When we go to Rome we see free men who have become bound by the delusion of power. They have anything a human being could desire on earth, and yet they are not completely free. They seek to destroy each other in order to have more power which in their view means more freedom.
Death
Spartacus says that death for a free man means loss of pleasure, but death for a slave means that he or she will be free from pain. For slaves, to die means they no longer are bound to the cruelty of a life in chains where their masters use them as objects. Where they are unseen in day to day life. As a plant would be, they are at best for decoration. At worst they are ordered to brutalize and kill one another for the pleasure of nobility and those in lofty positions. Death then becomes the only option for a slave. Running is no longer an option to gain freedom as it is only gained through conquering the oppressor or dying in the cause.
