Now, now, you know that Americans are disqualified from playing Bond.
No, but really, I think that Idris would be great. The issue is that I think he might feel familiar; like a more polished Craig. Doesn't do much to change the tone. If you're looking for something lighter, Hiddleston might be good, though I'm not sure I could take him seriously.
I know that this is out of left field/that he's not a viable candidate, but what about Colin Firth? He's still got the necessary sex appeal (was my ex's official "old man" crush) + would be great as an older, wiser take on the character. A way to tell different kinds of stories through the same franchise.