OK, I've made some comments by each, (above in red) JMO of course, and bearing in mind the short time you'll be here.
There isn't much in Deva IRRC, there is the ruins of a castle that was being 'renovated' with a cable car up to it and I think that is about it.
I would add Alba Iulia to that list, its rather impressive fortifications are worth a look, but again is quite a spin from where Clive is.
I didn't personally like Brasov, it was a little overcrowded with Americans when I was there, and a little touristy. Sighisora and Sibiu are nicer, though still quite touristy. I heard my first English voice in Sibiu for a week the last time I was there.
If your in that area, its worth peeling off to visit a couple of the fortified churches, like Biertan, not least for some of the quait villages they are located in. I'm not into churches at all, but I enjoyed the trip round three of them one day, though I actually only entered one (I forget which).
One of the highlights is the Ruins of
Sarmizegetusa Regia. Posted that as a link for you because I couldn't remember how to spell it for the life of me. It looks a bit dry in that wiki link, but the walls etc coming out of the forest lokk like something out of Asterix! And there is a lot of it too see with several sites all down the one gravel road. The sheer scale of it, given that is pre-Roman, in what the history book consider a 'barbarian' area is quite impressive.