To get back on topic...
AG is the best Trump will offer Cruz, i think. He won't offer him SCOTUS as he would be afraid Cruz would block his legislation purely for revenge. I doubt that Trump realizes that Cruz would weigh his decisions based entirely upon constitutionality as Trump does not have much understanding of our Constitution at this point in time.
If I was Cruz, I would not accept the AG position as that position rarely lasts long. Giving up a Senate seat to be fired doesn't seem to be a wise move to me. I would question Trump's motives.
I was anti Trump and wrote in McMullin. I generally like the way Trump and his team have operated since election night and I would very much like to see Cruz as AG.
But words are supposed to mean something. If Trump actually offers AG to Cruz he'll be demonstrating that he, not Cruz, lied during the primaries with his "Lyin' Ted" smear. The idea that someone would win the nomination by, in part, accusing an opponent of being a liar, *then* offer that opponent the job of chief law enforcement officer, is beyond absurd.
Of course it's just rumor at this point, but I hope Cruz would turn it down. Were I Chuck Schumer I would have no difficulty humiliating both Trump and Cruz in a Senate confirmation debate about Cruz for AG. Were I Ted Cruz I wouldn't trust Trump as far as I could throw him, and I would expect a high probability of serious conflict between a Trump WH and a Cruz DOJ.