I think that Romney should pick a moderate (center-left or center-right) as VP. If his goal is to take the election to the House, he needs to win over some center-left voters too. He'll need to win at least a couple of blue states (like Virginia or Colorado).
Here's a semi-realistic map where no one gets over 270 EVs:
Hillary Clinton: 268 EV's, 47%
Donald Trump: 160 EV's, 30%
Mitt Romney: 110 EV's, 20%
NOTE: I don't think that this map will happen.
I'm just saying that this is a possible map where no one gets over 270.
The reason I shaded Arizona and NC red is because of vote splitting.
AZ and NC could certainly go blue/green.
You guys have to remember that Colorado and Iowa absolutely hate Clinton and Trump.
I could see Romney winning these two states.
What do you guys think.
Why on Earth would Romney win here or Wisconsin? And you can't just say "vote splitting". The Democratic floor here is about 40% (basically Al Franken's 2008 numbers), so even if Trump collapsed here and ended in the single digits Romney would still need at least a quarter of Obama 2012 voters.
And those numbers don't reflect the popular vote at all. Hillary would be winning over 40 states if she had a 17 point lead on the second place candidate. You basically just took the 2012 map and colored some states green.