Abolish the EC and the candidates would focus on the large population centers, both parties. The Republican would start spending much more time in NY, for example. Though it’s normally a lost cause, without the EC, every percentage point swing is huge if it come from a large, densely populated region.
PA, OH, FL, CA. These are the kinds of places they’ll spend their time and focus their strategies. In fact, you can ignore states (to some extent). My state, PA, has Philly (and environs) in the southeast, Pittsburgh in the southwest, forming a sort of T-shaped area of the rest of the state. It’s been called “Philly, Pittsburgh, and the T is Alabama,” because the rest of the state is sparsely populated, and with a much more non-urban dynamic. The sort who cling to their religion and guns. 
So, a candidate can become even MORE selective. Screw the “T” in PA. Too few people–they only matter in an EC situation if the vote is close in the state. Unless there’s some statewide sensibility or benefit to campaign on, who cares about the rednecks in the T? Campaign up and down the NE Corridor, don’t stray too far from the coast (as one element of a “focus on the megalopolises” strategy). Play up to the urban and suburban commonalities as best you can. Do the same for other large population centers, and move the percentage meter as much as you can. You can move CA state a few percentage points? HUGE. You don’t need to win the state, just use your campaign time efficiently. Every speech in CA reaches WAY more people than one in WY.
The EC, as a matter of algebra, gives more weight (slightly) to smaller states. That’s what it’s supposed to do, so they don’t get completely ignored. To the extent any state is “ignored” now, large or small, it’s because they are a slam dunk for the other party. Take away the EC, and the areas that will be ignored won’t be tough to predict, and it ain’t gonna be the larger states. It will be most of the U.S., geographically, though. I think the EC is a nice compromise, a way for someone in Iowa (for example) to know their regional interests won’t get buried every single time. Same reason they have 2 Senators, just like CA.