If Gingrich is smart he should spend all his time and money in Arizona.
With Romney and Santorum duking it out in Michigan, he might be able to pull a surprise that will revive his campaign.
Romney is already spending money in AZ and would spend more if they were challenged. Plus Romney is spending money in GA (as is Santorum) and if Gingrich has any chance, he has to win his home state so they have to spend their few remaining $ on GA (he is also looking at OH as their one non GA Super Tuesday state). Of course if Sheldon Adelson gives Gingrich's SuperPAC $10M, maybe they will start to spread it around more.