Due to the combination of common demographics in certain areas (i.e.: urban liberal vs rural conservative, as one example) and advances in polls and predicting, the size of the state has become pretty much irrelevant. Small or large doesn't matter anymore, and said arguments have been reduced to red herrings... which, unfortunately, too many people still fall for. This is evidenced by the largest prize, California, getting only a couple token visits by candidates in the last few elections because the outcome in California was a fait accompli. The only states paid any real attention are the swings states, those close enough to actually make a difference in a tight race.
The candidates and their campaign staff know this, and play to it.