Jon Huntsman to lock up Utah
It's Romney. Utah would've instantly been safe.
"A woman" or "a Latino" is an obvious choice, but it's hard to say
who would fit either role. Rubio was a Romney VP finalist in 2012 but I doubt he would've gone for it. (The others were Ryan, obviously, Portman, and Pawlenty, none of whom seem likely to go for it in 2012). So, spitballing...Ayotte, Haley, and Sandoval all make some sense. Martinez fits perfectly, but probably wouldn't want it.
It also depends on what Trump does -- his four finalists were Christie, Pence, Flynn, and Gingrich, and he originally intended to pick Christie before Kushner convinced him to switch to Pence. If Trump does pick the very Northeastern Christie, or Flynn, who is outright pro-choice, it might behoove Romney to try to appeal to evangelicals in a big way, counting on Republican Hispanics/suburbanites to back him over Trump anyway. Pence would be a really logical pick, but he may not want to go for it. Some other evangelical politician, then -- Perry might actually be a logical choice, since he started off hardcore NeverTrump before suddenly randomly doing a 180, or maybe Haley Barbour. Jindal would be asking for trouble.