How do you keep your potatoes? I have the hardest time keeping them from going bad, I’m talking a few days max.
They're gone within two weeks, so I generally don't have that problem (I'm part Scots-Irish, I can eat spuds for dessert). The main thing is to make sure they are in a cool, dry and ventilated place that is very dark and that they are not just dumped in a drawer.
Potatoes keep about forever if they're fresh; (well, at least a few months) if they're kept cool. Finding them at a farmer's market or local farm stand is the best deal. The fact that they about rot after a couple weeks at home is an indication of how old they really are.
In NYS, there's two main areas that grow potatoes; highland and muck. The highland potatoes, which are grown in higher, drier conditions store much better. Some varieties store much better than others as well. It's worth looking into.