As for a qunari rogue, what spec were you thinking of using?
I like the idea of a Tempest. Pop a flask, then bam, a flaming dual dagger wielding monster in battle 
Tempest sounds interesting, the way you put it, and I should keep myself open to that. But if Assassin is anything like the DA2 spec, then I could end up going that route instead. I guess I'll have to see the full trees and perhaps some actual gameplay (have we seen Tempest in action yet?) before I make a decision. Or, you know, try both! 
Like Genshie, I'm also curious what you all think of qunari rogues. Part of me feels that warrior is the most in-character class for a qunari, given their size and strength (not to mention that 10% vs. melee racial bonus), but we did see some rogues in DA2, not only Tal-Vashoth but the Arishok himself. (Actually, I think rogues might have outnumbered warriors among the qunari in DA2.) Granted, it's their dual-wielding that means they must be classed as rogues according to the game engine, but I do like this idea that qunari can be dual-wielding rogues, provided their "daggers" are the size of one- or two-handed swords/axes. Since the devs have mentioned (apologies for the lack of an actual quote) that there will be some pretty big daggers in DA:I, I think a DW qunari rogue wouldn't necessarily be that OOC. Add to that the fact that a qunari inquisitor is Vashoth, meaning that s/he needn't subscribe to Qun mentality (and could be made to reject it entirely, depending on your tastes), I think an archer would be fine, too.
However, I agree that the size makes me just a little hesitant about a rogue. I can easily imagine a warrior or a mage towering over everyone else (or being relatively small, for that matter: dwarfs make great warriors and elves mages, for example), but a hulking rogue strikes me as a bit of an oxymoron. On the other hand, the unexpected combination could work really well, and I can't wait to see how it goes!
ETA: We did see a Qunari archer play an important role in DA2 (at the end of the episode involving Sister Petrice), so there are definitely archers among them.