Cassandra: She's a natural fit as a frontline tank. She seems like she'll be a tough, assertive, and trustworthy character, and I think I can count on her to either inform or challenge my decisions, and I value a character that can do that. She is by far the character I'm looking forward to adventuring with the most. And I think she's absolutely lovely 
Solas: He's interesting to me because of his unique and likely unrivaled knowlege of the fade and spirits. I am further intrigued because he has had no restrictions placed upon his education in the ways of magic, which to me means that he could potentially be one of the most capable and powerful mages of all time. However, he keeps to himself and seems to have a very level head, which tells me that he is also very responsible and likely incorruptible. Definitely someone I want to have on my team. I plan to focus his ability set on area damage spells and crowd control.
Cole: I really want to know what's up with this dude. And I need to have someone on the team who can wear glorious hats. I plan to spec him to be able to stealth a lot and deal ridiculous ammounts of single target burst damage. He'll be my go-to assassin when mages and tower shield guys show up.
And my Inquisitor will probably be a male Qunari archer rogue, artificer spec. I want to take advantage of the new option to play as a Qunari, and I think a Qunari wearing a long coat and wielding a bow would look totally sick. As an artificer, I imagine he'll be my primary crowd-control specialist, and I'm hoping he'll be able to deliver strong single-target sustained damage, because that would round out my group perfectly.