Speaking of the GOP, let's start there.
Texas is a showdown state — no other way to put it. Cruz has to win, and Trump would love a knockout. So, Lobster Claws Kasich and Roboto Rubio aka Marco Polo (thanks, Brains) should probably focus on other states, if they have brains.
The GOP has one other twist. Many of the states, even though not winner-take-all, have popular vote percentage floors, usually 20 percent. The NYT explains further, and the Washington Post yet further. For Kasich, especially, this is a reason to use his husbanded financial and staff resources carefully. Wikipedia has the details on threshold percentages.
Kasich, IMO, would be best targeting Massachusetts, Vermont and probably Virginia. Rubio could probably focus on all non-Texas states but those three, though he might eyeball Virginia, too.
Will "establishment Republican" Chris Christie's endorsement of Trump help Trump that much? Hurt others? I doubt it. Their political circles may not overlap quite as much as the geographic ones, but they do enough, and Christie was always yesterday's news in the GOP.
The GOP has the additional twist that more than half the Super Tuesday primaries are open, though I don't see any likelihood of major Democratic crossovers. Alleged independents? Different story, and will surely break for Trump; let's see how many participate.
Democrats? Same on open vs closed primaries. Given low party turnout so far, the number of primaries that are open will be a good measure of Democratic support. Given that many of them are southern states, I predict turnout will be abysmal.
Sanders needs to win the more liberal Massachusetts and Minnesota, as well as home-state Vermont. Targeting black votes in urban Massachusetts would help his reputation there. Virginia could be a good target, even with the inside-the-Beltway issues he'll face, and Texas has to be contested because of total delegates. Sanders also might play well in Border South Oklahoma and Tennessee. Anyway, he has to win states besides Vermont. Another one he needs to do well in, and, realistically, win, is Colorado. Getting youth and young adults to turn out in places like Boulder will be key — and perhaps heavy work, as Colorado is a caucus state.
And, in pre-Super Tuesday, will Hillary's being called out on her 1996 super-predators have any effect? Moral victory plus spinning for Sanders would be losing by less than 15 percent.