Proportional Representation

In my political science class, my instructor brought up a very interesting question concerning whether or not should the United States have proportional representation. I think that we(considering I'm a citizen of the United States) should not have that type of system. People in the same party can barely agree on policies together, so i doubt if many parties can come together and agree on serious issues. With a system like proportional representation, it strongly involves a coalition and I sincerely don't see that happening now-a-days. I don't think we should have the dominance of just two parties neither though. I believe the United States focus should be on developing a new effective system of democracy. The people of the country should severely decide on many decisions, but then there is the fear that the people don't know how to accurately decide on critical policies in the country. My question is what the use of a democracy if the people don't get what they want and need? The main focus of the government is to serve it's people and make life more comfortable for the citizens. How is that true if we cant decide on policies? Many people don't understand that an administration is not going to be perfect in every aspect and that they are going to fail every once in a while, but I truly believe we should consider a new format of government that is more appealing to more audiences.