As a complete outsider I don't think it's my place to suggest any big issues for the presidential candidates to deal with. However, there are some smaller issues on which I would find it very enlightening to hear the candidates opinions.
From a human rights perspective I would very much like to learn whether or not the candidates are planning to uphold the American Servicemembers protection act, not only because of the "The Hague invasion clause" embedded in that act, but also because it embodies the current stance of the United States of America to the ICC.
Another smaller issue on which I would like to hear the candidates point of view include their ideas about the trias politica, and the specific division of power between the executive, legislative and judicial branches, as that division seems to have become somewhat muddled lately.
At any rate I would like to hear less about the fact candidates wanting to restore the prestige of the USA and more about how they intend to do this.