The novel describes Sollozzo and Brasi as men who radiate danger. The cast for these characters was perfect, I think.

I think that GF2 was a great film, but it lacked dangerous characters.
Roth? Too old.
Neri? We don't see anything really threatening of him. He washes his hands after the murder of the prostitute and (in the delted scene) slaps the owner of the casino.
Mike's bodyguard? I wouldn't want to meet im in the street at night, but no comparison to Brasi. Too soft and old.
Fanucci? Forget it.

And in GF3, every opponent is old. Mosca's nephew (or was it his son?) - ridiculous. The twins look like opera characters.

That's a good point, Danito.

I think what you observe is not an accident, but a natural effect of the changes in the Mafia and the country as time moved on.

Michael (and Roth, and Lucchesi) thought of themselves as businessmen and operated in a totally different realm than Vito did. They couldn't surround themselves with overtly dangerous characters, and kept great distance between themselves and the violence they had a hand in.

There is one dangerous character in GFIII - the Ant. He is the exception that proves the rule, serving to illustrate the difference between "businessman" Michael and "common Mafia thug" Zasa.

I think it has more to do with film making, casting and intensity.
For example, they could have taken more time for casting Michael's bodyguard.
And the Ant? "Za-zoom-za-zoom..."

Radiating danger makes other people wary. Roth was by far Michael's most dangerous adversary, in part because he didn't radiate danger. His kindly, paternal manner and seeming passivity almost cost Michael his life and his liberty several times.

I agree with Turnbull and would add that deception was a key theme of GFII. Michael wanted to appear cooperate and to be Roth's understudy, but beneath the exterior was planning to overtake Roth. Roth appeared to be friendly ex-partner of Michael's father, but instead was trying to kill Michael in order to prevent being muscled out of Havana.

Roth was as dangerous - and maybe moreso - than even Sollozzo. I think Roth's key weakness was underestimating Michael's ruthlessness. I would argue that Roth radiated danger in his complete duping of Fredo. Roth almost succeeded in having Fredo play the role of having Michael killed, all the while with Roth pulling the strings but nearly avoiding detection.

No question he underestimated Michael, but I think his real weakness was his hubris. He thought he was the smartest guy on earth and it never dawned on him that Michael saw right through him until it was too late. This explains his outrage at Michael when he realized Michael might be backing out of the Cuba deal.

Roth's other weakness was greed. He could have had Michael whacked as soon as he arrived in Cuba, but he held out for that $2 million until even after it seemed clear that Michael was on to him.

I knew it: Just when I thought I was out and tried to talk about acting, directing, casting, they pull me back in the story as if it's real.

What about my namesake? I think he radiates danger. Same with Rocco.