Screw Wal-Mart. I'm grabbing my guns, generator, welder, change of clothes, and my coffee mug, hopping in the truck and heading for Tractor Supply Co for some prefilled Argon bottles. Next, I'm heading to Menards (a huge hardware store that also sells basic food). Why? Because unlike Wal-mart, Menards has tons and tons of tools, building materials, metal objects, etc... not to mention fork lifts, delivery trucks and contractor 4wd pickups. Plus, Wal-mart has WAY too much food. If there's a power issue, you'll be surrounded by rot, rodents and insects. Screw that.
I'm beefing up my truck (that's what my welder, the Argon and the stock metal/random metal objects are for). I'll then build a very secure room inside the store (building materials and tools are everywhere, so this won't be a problem). I'll rig up some booby-traps and intrusion indicators. Then I'm heading for a gun store. On the way, I'll stop at the local police station. The evidence room should have enough firearms and ammo to last me a while. If the evidence room is empty, I'll continue to the gun store. If it's not, I'll grab everything and return to Menards.
That's the first day. I have no specific ideas about the long-term. I think that life on the move would be pretty smart. Maybe head for Montana or Alaska or something. But I would definitely stay at my safe room in Menards for several days until I could put together a good gameplan.