Basically, there were two major war aims for the Americans: stop the Brits impressing their sailors and conquer land in Canada. Impressment ended up a moot point, since the British abolished it anyway as the Napoleonic Wars wound down, and the conquest of Canada didn't work out. (Obviously; that's why there's still a country called Canada now.) And whilst none of the British counter-attacks had taken any major strategic targets (although capturing Washington was a great propaganda victory), the Brits had managed to extricate themselves well enough, and there was every reason to suppose that they'd be back again next year. Meanwhile America was on the verge of bankruptcy and finding it difficult to make good its losses because nobody wanted to fight in an unpopular and losing war. Really, the fact that so many people in America seem to consider not being conquered as a victory shows just how bad things had become.
Anyway, as said on the other thread, the Brits probably wouldn't be interested in taking too much land even in the event of a total US collapse, since their ambitions and efforts had moved elsewhere after 1783. Michigan and Wisconsin would be plausible demands, since they'd increase the strategic depth of British North America and weren't incorporated as US States, meaning that it would be easier to reconcile America to their loss. Maybe if things went really well and Tecumseh was still around they might demand US recognition of his confederacy, but that would be about the limit of their demands.