Stores are cool but if the magma hits the fan, things get bad quickly because there's only one exit.
I had a serious situation recently on my current life. I holed up in a pharmacy that had been mostly cleaned out by four or five survivors. We camped out for a while, I traded what I could for some medkits and pills, and then noticed there was a zombie in the back of the store. It got someone, they both started roaming the shelves for more victims. I headed toward the front hoping they would stay back there, only to find a zombie master and his entourage moving in the entrance. I headed down to the southern part of the store (Entrance was in the east, it was rectangle, long sides horizontal) and started running as the other survivors got massacred. I ran to the back of the store, shooting one of my former companions with a hunting rifle, and made my way north, pushing shelves to the side so they couldn't get me. Even so, they came up at me as I headed for the exit and I barely made it out.
Now I'm in a sporting goods store, and there's a general store just across the street that hasn't been touched. I have one person in the store with me, and I'll ally her once I get leadership. Things are looking up, which means it's going to get horrible soon.
Also, what do you use spraycans for? When I find them I usually use them to mark my base, any other uses people hav efound?