Re: The Sentinels
I think for me the most important part to get right is the facial and head design, that square, lifeless and angular feel. As for the color, I think dark purple and black would be a cool combo, being both – for killer-robots – cinematically unique and with a nod to the comics. Metallic grey would be a safe and solid choice but with the risk of becoming a bit too plain looking or too – in the future context – Terminator-ish.
I want them to be quite big, but 50 feet seems a bit excessive. I rather them be slightly less big and have more of them at the same time instead.