| and one reason why Raimi has Tobey frequently seen without the mask). |
I thought that was to frighten children!

Whoever they get, it needs to be someone who can act THROUGH the mask, and I don't mean like Willem Dafoe in the Power Rangers villain get-up.
Peter Weller still had his mouth to work with, and the filmmakers did occasionally find ways to bring his eyes into it as well, but that's the general direction I'm thinking as far as what kind of presence and ability is needed to be convincing. It's a tall order to fill. Iron Man will have to act convincingly through movement and posturing in the suit coupled with well-done ADR.
I know he has his share of detractors, but Billy Zane may have enough presence to pull it off.
He was all for doing more Phantom movies; unfortunately, it bombed. Of course, I liked it. Had some campy elements (mostly Treat Williams), but I thought he was an excellent super hero. He could certainly give Stark some smarmy, billionaire playboy qualities as well. If the director's ballsy enough to not let him go over-the-top (something few directors seem to be capable of being with Mr. Cruise), Zane could be a good Iron Man.