As someone who supported Obama right from the beginning, I am quite pleased to see him clinch the nomination. I supported Clinton's right to stay in until the primaries ended, but now is the time to bow out and throw her support behind Obama. The longer the party remains divided, the better the chances are of McCain winning. Now the focus for the Democrats must turn to beating McCain in November, which contrary to what some think, will not be an easy task. McCain is a moderate within the Republicans (although quite right wing by Canadian standards) so unlike Huckabee or Romney, he has a far amount of crossover appeal to moderates. In addition, he voted against Bush on a number of issues so although being a Republican may be a liability, the fact he didn't blindly follow in lock step will be an asset to him. Unlike Canada, where one is expected to tow the party line, senators and congressmen are free to vote against their party without facing party discipline. At the same time McCain does support the war in Iraq and is still more conservative than the average American even though the average American is well to the right of the average Canadian. This has been an interesting race in the sense neither of the frontrunners of either party ended up winning. A year ago, most thought it would be a battle between Guiliani and Hilary Clinton, but instead that will not be the case. Guiliani's campaign fizzled quite early on, while Clinton stayed into the very end, but still could not win the nomination.
As for where from here to go for the Democrats, Obama needs to choose him running mate. Although I would say he should choose Clinton, I don't think it is essential he choose her. Rather he must choose someone who appeals to the demographics he is weak amongst. In particular, he struggled amongst white blue collar voters and this demographic is very important to winning in November. He may be able to pick up states like Iowa and Colorado while hold ones like Wisconsin, however states such as Michigan, Pennsylvania, and Ohio have far more people than the ones mentioned above. Obama cannot afford to lose Michigan or Pennsylvania and likewise will have a difficult time (although not impossible time) becoming president if he cannot win Ohio. These states all have a large blue collar white vote, which is why I think he needs to choose a running mate who can appeal to this group. I don't think the fact he is black will prevent him from becoming president since although some Americans are still racist, they are clearly in the minority. In fact I would argue a black person would have far more difficulty winning in most European countries than the United States despite the fact Europe is generally more liberal than the United States. His biggest liability will be being seen as too liberal. His platfrom is fairly centrist and in fact in relation to Canadian parties, is probably, closest to that of the old Progressive Conservatives, so he needs to highlight the fact he is moderate and not a liberal. As much as some progressives want to see the US move dramatically to the left, they need to be realistic. Trying to move the US as far left as Canada is simply not realistic. Rather the Democrats need to halt America's move to the right and take a more moderate centrist approach than the current administration. That is why I would advise Obama to focus on ending the War in Iraq but still support the use of military force if the US is attacked. Support tax cuts for low and middle income Americans, and make clear that the overall size of government will not get bigger. I have noticed some liberals talk about the US adopting universal health care. As much as a supporter I am of universal health care, bringing in such a program would be political suicide in the US. Instead progressives need to be realistic on what is doable rather than what is not doable. Just because a certain policy sells well in Canada, doesn't mean it will in the US. As Micheal Adams pointed out in his Fire and Ice - Myth of Converging Values, Americans and Canadians have radically different set of values.
In terms of Canada-US relations, I think the Democrats on the whole would be better although I do realize on the issue of free trade the Republicans are probably better, however the Democrats would be at least more understanding on most other issues. Besides, with more than half of Canadians having at least one family member residing outside of Canada, Canadians tend to take a very internationalist approach, so even if McCain is better for strictly relations between Canada and the US, they realize he is not better for relations between the US and the rest of the world.