Foreign policy should be No. 1
I think the presidents main job in any administration should be foreign policy. The president should spend the bulk of their time outside the country helping to establish, augment or leverage relationships around the world to improve the environment for Americas citizens and corporations. Domestic policy can be driven by the Congress and respective states, with obviously the presidents veto power acting as a check and balance. The need to focus internationally is magnified in this election due to the war(s) and the significantly eroded opinion of America held throughout the world after the Bush administration many abuses.
There are obviously many domestic issues that are also important to me (e.g. the farcical war on drugs, the civil rights issue of gay marriage, the Social Security ponzi scheme, fear of the Democrats attempts at nationalizing health care, an increasingly re-distributive tax code and general intrusiveness of the federal government both economically and personally) which will have a significant impact on my vote.
That said, my No. 1 issue of this general election cycle (if it ever gets started) will be how Obama and McCain discuss what will be their efforts to re-establish diplomacy around the world and repair Americas name in light of the Bush administrations numerous international missteps and abuses of power.
(continued) The major Bush administration scandals can be divided into two groups: human rights abuses (e.g. Abu Ghraib, waterboarding and other forms of torture, holding (kidnapping) suspected enemy combatants indefinitely in Guantanamo Bay without charging them for any actual crimes) and abuses of presidential power (e.g. excessive use of signing statements, The Patriot Act, warrantless wiretapping).
These are but a few of the gross missteps made by the Bush administration that have shown a complete disregard for the Constitution, international standards and general morality. I currently believe that Sen. Obama is the most likely to speak most openly with the international community about these abuses, and more importantly, end them.
Just leave NAFTA alone.