The Green Mountain state profoundly shaped my perspective about how my particular progressive political views intersect with electoral politics, policy-making, and governance, though in my case from the late 90s when I lived there. There is also a wealth of experience regarding left alternative party building in the state, both good and bad.
I also agree Fladem that perhaps the biggest flashpoint between 'liberals' and 'progressives' is found in foreign policy and more or less in the way you frame it: Is American foreign policy generally imperialist or something else and something of an exception to world power politics? But as one might expect from a 'socioeconomic progressive' that is to me just a subset of the larger questions about market capitalism. US foreign policy is at its core about extending and protecting a US-dominated global capitalist system. There really is not much room to debate that, it seems to me, only whether or not that is a good thing.
Up thread you ask 'what is the alternative'? By way of quick response I'd start with:
(1) nothing is more unrealistic or unsustainable than global capitalism and the longer the delay to transition away the rougher it will be and the worse will be the outcomes - presumption is against the status quo;
(2) much of human social experience right now - today - is not subjected, or at least not willingly and readily, to market logic. In my view, the challenge is to 'protect' those areas as much as possible from the application of market logic. These include things like family life and public goods, and market promoters are relentless in their efforts to extend the logic of the market to new profitable areas. Enclosure continues as the market reaches and consumes ever more of human social life. A litmus test of a sort is for me water: should water resources and their delivery be privatized or not? One cannot support privatization of water and be a progressive, in my judgment, under any conditions whatsoever;
(3) the possibility of alternatives and the worst consequences of the current system are most visible from outside the US political context, for the most part. Something to think about;
(4) there is The Market and there is the market. Free market advocates often perceive critics as somehow anti-trade. That is not entirely unfair in some cases in as much as many progressives (and ecologists) encourage local production and consumption over disaggregated production and consumption systems across the entire globe. But that is really just a shift in the locus of trade. But more generally, and in a highly, and perhaps uselessly, abstract way, progressives can embrace a market in which monetized trading practices are permitted but which are embedded in and subordinate to larger social structures and rituals that reflect communal values. Then there is The Market, which is the thing US and most global elites promote as the highest and best form of human organization that can ever be achieved, so don't even contemplate alternatives because there are none (that is the ideological function of the TINA refrain);
(5) the long term alternative - in my own view - is to leverage our way into social democracy and greater ecological restraint on our way over many generations to bioregional political federations as a type of libertarian socialist socio-economic configuration. But that is so far off it is usually pointless to engage in discussions about such matter, at least not until the wee hours of the morning after a lively evening.
Plenty of ideas to comment on there, IMHO. What think you?