The reality is that you're going to get press whomever you get to speak-why not go with people who do it for a profession? The best kind of celebrity moments, the ones that bring you the most buzz, are when political celebrities step up to the stage. Think of men who crossed party lines to give a speech at a convention that was not one they'd devoted their lives toward (Zell Miller, Joe Lieberman). Think of superstars launching their careers (Ann Richards, Barack Obama, Julian Castro). And think of family members giving compelling testimonials for their presidential husband/father (every convention ever). The thing is that you're going to get a bounce from the media, but using celebrities as a crutch isn't going to be as compelling as having both entertainment and substance, and while people will watch, it's the media that will ultimately frame whether or not you exceed expectations-play into that hand and give them a largely fiery, partisan slate of speeches that will also arm surrogates who are wearily staying off the stage in Cleveland with a litany of talking points to make your case back in their states.
So you need someone who can both be a competent attack dog against Hillary Clinton, do well enough in the debate against her eventual successor, and yet has so little career left (or is in a state that matters so little on that front) to be willing to back literally all of Trump's policies. If Ernst thinks about her career (in a swing state) for longer than two seconds she doesn't seem like a viable option considering Trump's current standings in the polls. I like the idea of Jeff Sessions in some ways, but he has no fire power. And lord knows Trump owes Chris Christie enormously for essentially giving him the nomination, but Christie is too much damaged goods and the biggest punching bag/loser on the list, and wouldn't be a surprise at all (man how the mighty have fallen there). As a result, I'm going to take a move out of Bill Clinton's successful 1992 playbook and recommend former House Speaker Newt Gingrich, a clone in many respects to Trump in terms of personality. Gingrich also is more than willing to say whatever it takes to win over a crowd, but has the policy experience to know exactly how to go toe-to-toe in a debate and adds a legitimacy for the very conservative branch of the Republican establishment. He's the best reminder of easily the worst time in the Clintons' lives (his image brings about Whitewater and Monica Lewinsky), and he's smart. Gingrich is a double down strategy-a second Trump, and someone who can push Trump's policy to areas like Georgia, North Carolina, and the Florida panhandle as Trump has struggled more than your average Republican in securing the South.
My recommendation would be to not do it. It's questionable whether or not this is legal, for starters. There is an obscure article in the US Code that prohibits announcing cabinet appointments prior to the election, or at least it seemingly does. It's hard to tell in the code whether or not it's illegal to announce cabinet appointments or just that it's illegal to do so in hopes of securing a person's support of your candidacy. No candidate has ever done this before publicly, though it's hard to know exactly what would happen if it did and it's near certain that candidates have jockeyed around positions like Secretary of State and Attorney General to former opponents on the fence about their candidacy. I think a quiet campaign of letting certain names sift into the public conversation (provided it's legal-I'm not a lawyer and don't want to advice doing something that violates the US Code) would be a better choice. As for whom he'd pick if he did announce, of the top four cabinet positions, I'd probably go with John Bolton at State, Carl Icahn at Treasury, Chris Christie at Justice, and Michael Flynn at Defense, particularly if he decided to name in advance (there's not a lot of diversity there, but that doesn't seem to be a trait of particular value to the Trump campaign), but the reality is you'll get a better slate if you actually win since becoming Secretary of State goes from hypothetical to near certain in that case and more people are willing to get over Trump as a boss if they get to hold their dream job, and as naming the candidates in advance probably adds little to this list (your average voter has barely heard of Christie-the other three are all just very powerful men-about-Washington), there's no reason to do so other than the VP slot.
What I'd propose is a narrow inside straight to the White House, as it appears to be Trump's best option. From a tactical standpoint, his best bet is not necessarily to go with the same map that Republicans have gone after for years, but instead to sacrifice a state that I think will be close, but off the table: Florida. Don't publicly give it up, but instead assume you're going to take all of the Romney states (dispatch Christie, Gingrich, and everyone to those states throwing out red meat), but keep Trump on the war path in states like Pennsylvania, Ohio, Virginia, New Hampshire, Iowa, and Wisconsin. If he was able to win all of those states, plus those held by Romney, he would win the White House. Florida, with its high amount of Latino voters, including its Cuban-American population who seem primed to go to the Democrats (they historically have been a stronghold for Republicans) this year with both a relative popularity in regard to President Obama (over the end of the Cuban embargo) and due to Trump's immigration policies, seems like it is a lost cause for Trump to actually win, though I think he can come close. The same could be said for Colorado and Nevada.
But the Rust Belt states, considerably whiter and much more amenable to Trump's message on turning around manufacturing, is going to be where he has the best spot. This is also where Trump's greatest advantage is going to be turned into an asset: the media desperately wants another horse race for ratings. This means that the media doesn't want a blowout ala 1996 where Clinton is clearly going to win and there's no spin to happen-they want another race like 2004 where the race's results aren't known until that Tuesday night. People will tune in and pay attention to debates, races, and the news, which means ratings, if they think either candidate has a chance to win. As a result, they're going to try to make Clinton's negatives equal to her Republican opponent's (which, even from a nonpartisan perspective, are lesser than Trump's). They're going to talk about Brexit, a political realignment, and Benghazi/emails ad nauseam to ensure that people think either side could win. Trump would need to use that to his advantage as the person people think will win oftentimes is the one that actually does, even if personal preference polls show something different. Playing up Clinton's comments on coal and trying to make a strong case against trade pacts is one of the few cards in Trump's hand that's actually worth something still. If I were his campaign strategist, I'd have him in every Rust Belt and Midwestern venue he could find talking about how blue-collar workers were left behind during the Obama administration. It's a powerful message because those workers, some of which have historical ties to the Democratic Party, already believe it.
There you have it-my thoughts on what Donald Trump would need to do in order to be successful in November. While I go feel extremely gross about advising Trump, you share your thoughts-in playing devil's advocate, what does Trump need to do in order to actually hit 270 in November?