Perhaps even Vito “there is a lot I can't tell”!

Whilst the key was always to kill Vito sooner or later....yes or no....to the drug deal
When was Vito's mind made up about Sollozzo's, Sicilian and top narcotics man, drug deal?

Vito asked Sonny and Tom for their take, when they discussed the up coming Sollozzo's meeting. among others -

Sonny “There's a lot of money in that white powder”

Tom ”There's more money potential in narcotics than anything else we're looking at”

Sonny even asked “So, what's your answer gonna be, Pop?”

So Vito knew both Sonny and Tom were keen still doesn't excuse Sonny's out of turn blunder though

Sure thing “(It's Tom's counsel that give us the entire premise for the movie!)” but in fairness to Tom, in this instance, it seems, Vito had kept both Tom and Sonny 'pretty much in the dark' not discussing his decision with them prior to the meeting and both were “totally in the dark” had no idea Vito had sent Luca to Tattaglias thus to Luca's death

However Tom didn't dig into Sollozzo deep enough eg: not finding out Barzini's was the puppet master

However if Vito had “already made up his mind to say no to Sollozzo” before their meeting why didn't Vito inform Sonny and Tom accordingly unless the decision was made at the meeting which seems unlikely, if my memory serves me right, there was no additional information revealed by Sollozzo except the profit sharing and the million dollars finance

The reason for Vito's no to Sollozzo drug deal was because “drugs is a dirty business” nothing new there

I also believe, Tom would have consulted with Vito before Tom “communicated that the family would interested in hearing about Sollazzo's deal” “If nothing else, that would be very out of character for Tom”

It seems Vito's mind was already made up before the meeting and Vito only saw Sollozzo because Vito “heard that Sollozzo is a serious man, to be treated with respect”

However valid point “Ten years ago, with Genco as consigliere, I don't think Don Corleone takes a meeting with Virgil Sollazzo at all, and certainly not to tell him, "No”

And it was Michael “We can't wait. I don't care what Sollozzo says about a deal, he's gonna kill Pop, that's it. That's the key for him. Gotta get Sollozzo” whereas Tom wanted to wait!

“And Vito, well, Vito was, well...”!!

I'm guessing that it was Mob protocol. As Lana said, Vito probably decided against the drug deal long before he met with Sol. But, Vito was known as "a man of reasonableness," which helped him in his diplomacy with other Dons during peacetime. Refusing to see Sol, who was in effect sponsored by the Tattaglias, would be unnecessarily rude, and would cause bad feelings--or worse. Vito probably kept putting off the meeting with Sol, which was why Tom pressed him for a date.

BTW: There was more to Vito's opposition to drugs than the threat to his political base. In the novel, he tells Tom: "What he [Sol] will propose is an infamia."

Vito known as "a man of reasonableness," which helped him in his diplomacy with other Dons during peacetime. Refusing to see Sol, who was in effect sponsored by the Tattaglias, would be unnecessarily rude, and would cause bad feelings--or worse

And the meeting wasn't the problem - the refusal was. Had Tom counseled Vito not to meet, things would likely have proceeed the same way

Yes, I remember that condemnation. Puzo wrote that Vito was "notoriously straight-laced in matters of sex." That was confirmed when Puzo wrote about young Vito, after he met young Clemenza, and they stole the carpet out of an apartment. Vito still needed money because, as Puzo wrote, "He couldn't eat the rug."

[*]Yet Sollozzo told Tom after 'kidnapping' Tom “And you knew it was the right thing to do" As Turnbull already pointed out “How'd Sollozzo get that impression?”.
[*] Tom also found out about Tattaglia connection which Sollozzo hadn't revealed, as evident from Sollozzo's “my compliments
[*][/list]

It seemed Sollozzo hadn't revealed the Tattaglia connection ie: Sollozzo still gotten to see Vito without using a major family vouching for him as leverage

Was Barzini's beef personal?
I think Barzini's moves against Vito were "personal" in the sense that he thought of himself as No.1 waiting in the wings, impatient to be the top dog in NYC, younger than the other Dons, whom he regarded as "Moustache Petes" (per the novel). But, I don't think he had a personal grudge against Vito

And ultimately that's why Barzini wasn't as great as Vito. Vito took EVERYTHING personally despite his outward statements that he didn't (take everything personal).