A Paradox of Democracy

So I only have one political philosophy class under my belt, so maybe this is already a dilemma in the field. But I realized a bit of a problem with democracy and the 'rational voter' about a week ago. Hopefully I will explain this problem well enough that someone will have a satisfactory conclusion. Because if not, I will probably just ignore this problem when it comes time to actually make political statements and vote.
Ok--so, for simplicity, let's say that voters are generally rational, but not omniscient. They have two options: a) Vote for what they feel is best for the country (or possibly the world), or b) Vote for what they feel is best for them personally.
Now it seems that most people I've asked think that a) is the best option. I agree. However, we are not omniscient, and in fact, the vast majority of us lack a large chunk of relevant information. We really only go off of our own experiences and what little research we do read in newspapers, magazines, or television.
Let's take, for example, the economy. I know nothing about the economy. Is it true that the tax cuts for the rich stimulate the overall economy enough that it creates jobs? I'm not sure. Maybe. When it is an area of debate to even highly educated economists, how am I to decide what is best? I have to take a leap of faith based on anecdotal evidence, at best. Virtually all issues are this way. Health Care, Education, the war, global warming, etc.
Now if all voters (whom we have agreed are rational and not omniscient) decide to choose option a), it seems like we put our trust too much in what magazines, books, TV, newspapers we read and the selected information they give to us. Don't get me wrong, I'm not crying conspiracy here, I am just saying that we only have so much time to do research, and regardless of which sources we choose for information, it is a limited amount of sources, which taints everything from the start.
So a), although well meaning, would cause the majority to vote for whatever is the most rational choice given whatever information is most widely publicized or read. And this doesn't seem right, unless we assume all relevant facts are widely publicized.

b) is ideal, in theory. If all voters are rational, they vote for what is best for them, and whatever is best for the majority goes. But isn't there something counterintuitive about such blatant selfish voting? For example, I don't know anyone who has died in the war in Iraq. So as a rational and selfish voter, I just shouldn't give a damn about that issue at all? And the Iraqi civilians, hell, I have no chance of knowing any of them, so I shouldn't take that into account when going to the booth?
Should I vote against gay marriage? After all, I'm not gay, and it would mean more of my tax money spent on federal benefits that I am already eligible for.
Should I vote for ethanol? It is great for the economies of the midwest, so shouldn't a rational midwesterner vote for it, regardless of the fact it uses more energy in fossil fuels than it produces?
Should I vote against national healthcare? After all, I have insurance, so I have no worries.
Maybe I have too strong of a conscience, but this just doesn't feel right.

So how do we solve it? I have no idea.

Oh...and they don't have bagged cereal here. Actually, we can't find any generic cereal, aside from ALDI. What is that? Thank God for Aldi.