Here's my 2 cents, for what it's worth.
ISIS: The terrorist acts in Paris have galvanized desires for another multi-trillion-dollar war in the Middle East, but that is barking up the wrong tree. The main source of Islamic terrorism is young, disaffected kids in the West and their radical clerics, not ISIS. Moreover, a large NATO invasion over there is unlikely to achieve much. If successful, a ground war would eliminate all ISIS territory, but it would not reduce terrorism in the West unless it were followed by stability in Iraq or Syria, for which there is currently no mechanism. So I think that, for the time being, the present strategy of military containment and diplomacy is the right one. In the end stability will have to come from within Syria and Iraq and from neighboring forces, with our strong encouragement. As for Assad, we may wish for his departure, but a stable society in Syria must be the initial and primary goal.
Terrorism: The origin of of Islamic (and other) terrorism is primarily at 'home', in the radicalized inhabitants of Molenbeek, Saint Denis and other areas of immigrant poverty in the West. It is there that our 'war' needs to be prosecuted. But to succeed it must be be a war of ideas and of policing, with more in common with the failed 'war on drugs' than with any military invasion.
We need to control the radicalization of young Muslims in the West. Easier said than done? Sure, but with more teeth than invading Syria or Iraq could have. Our schools need to effectively educate teenage kids that radical Islam is false and wrong. But we need tougher stuff as well - I would advocate for an outright ban on Radical Islam in the West, even the non-violent kind. No preaching and no advocating it in any circles, even at home. A ban on Wahabism and Salafism. A ban on associating political preaching within Islam. Is that hypocritical? Why not ban fundamentalists from other religions too? Well, simply because they are far less likely to become terrorists (although it has happened occasionally, including, recently, here in Knoxville). Moreover, and here's another controversial step: I would suggest a kind of affirmative action in Muslim communities, offering significant financial and other incentives to people willing to provide names of radicalized individuals and 'cells' in their communities. Its not enough to say 'Muslims should be doing more to root out jihadists from within': they need to be incentivized. Radicals need to be identified with all means possible and, before they have had a chance to think of violence, reeducated. Laws should be passed permitting electronic tagging of identified radicals, and there must be increased border security, preventing direct or indirect travel of anyone to or from Syria or Iraq until peace is reestablished there. Moreover, greatly increased electronic surveillance and interception will be needed. The downside of what I am thinking of is that it would presumably be hugely unconstitutional here in the USA, trampling all over liberty, free speech and privacy rights. It would involve moving towards a Stasi-esque, police-dominated culture in Western communities in which radicals are found, in which thought is controlled and community members are encouraged to spy on and shop their own family members and friends. How sad! But it would be effective, I think, for now, and maybe not so draconian in the end. After all, Germany has had laws preventing home-grown Nazism for decades. Later on, when the threat recedes, the grip should be released.
The Refugees: For a number of reasons I would not advocate the rapid settlement of large numbers refugees in the USA. However, fear of terrorism is not one of these reasons. The primary reason is that any immigration should be driven by the economic needs of the USA, and another is that I'm generally not in favour of population expansion anywhere as goes against my vision of what the Earth should look like. But we cannot abandon the refugees. We are not blameless here. We invaded Iraq, alienated Iraqi Sunnis, destabilized Syria etc. and this led in no small part to the present strife and the refugee plight. We need to help them, with immediate large, amounts of aid to them in the countries to which they have already fled, followed by controlled, slow immigration of some of them to the rest of the West. They are indeed our problem and we must not ignore them.