Depends on how dark you want to really make your campaign (ie age of group in reference to "adult" type themes...)
The campaign I'm currently running is basically a war where there is a more powerful enemy taking over the world, while the heroes help to fight as part of the rebellion to stop him.
for some ideas you can use:
NPCS: (you'll have to do names - I always have trouble with that part)
Captain of the Hammerhold Guards:
A career soldier, doesn't really buy into the BS of politics, and tends to do what he thinks best, even if it involves going around his superiors - this could lead to him using the heroes to solve problems even if the city officials don't really like the idea (think commissioner Gordon utilizing Batman even though he's a wanted vigilante)
This can also be used if you have the heroes become not liked by the people of the city for some reason, perhaps the officials blame the attacks on the heroes interfering with the goblins and the goblins striking back - the badguy you have leading the goblins could even help out with this by sending messages saying they are attacking in retaliation for the heroes attacking them in their lair...
Some ideas for adventure hooks... when the attack on Hammerhold happens - those left in the city when it's overrun are taken as slaves - this can lead to the daring rescue by the heroes...
Also - when there's a war going on - a good adventure hook is the classic "we think x item will turn the tide of the war - can you go retrieve it?"
Also - you can use a similar idea to what I've done in my campaign - basically the heroes started working for the "good guy" leader, then found out that he was actually playing both sides, and basically just keeping the heroes out of the way while he seized control and used them to gather things he needed to stay in power
Twists like this can be quite entertaining, and can lead to interesting roleplaying situations when they realize that the suffering and death may be partly their fault, and try to rectify it.
Perhaps this could even end up with a tie-in to the Guard Captain from earlier, he does what he can from the inside to undermine the leader and help the heroes to oust the bad guy that the heroes inadvertently helped to power, he can see that the heroes were manipulated just as he was, and does whatever he can to help make it right.
Magic is a great way to let the bad guy play both sides - perhaps as an advisor to the city who eventually gets put into charge (in my case he was advisor who was placed in charge when the leader died with no heir) and once he was firmly in power, revealed that he was leading both groups - but this isn't necessarily needed - think Darth Sidious in the star wars prequels for a great example of this - he plays both sides to war with each other, takes over and ends the war looking like a savior, while enslaving the people "This is how liberty dies, to thunderous applause"
Some other interesting NPC ideas - perhaps a city leader/sect that hates magic and shuns magical races, and attacks magical beings, trying to eradicate it.
feel free to hit me up via PM if you want to bounce ideas back and forth - I'm always up for some creative brainstorming and I'll gladly help as best I can
"Human beings are almost unique in their ability to learn from the experiences of others, and in their apparent disinclination to do so."