Definitely. I've said this for years. The only doors in and out are three steel roll shutters and three steel emergency exit doors. All the loading docks are about seven feet off the ground, and should it get bad enough, those steel doors can be reinforced by ton's of shelving that can be locked into brackets on the wall and weighted down with hundred's of tons of goods that you won't be using. Those doors will stand up to hundreds of zombies.
In a typical Costco, there is enough bottled water for a group of twenty people to survive on two bottles a day for 2 1/2 years. Not to mention the bottled juices, sodas, and beer. Food wise, you can last up to a year or more as well, as long as you are careful and smart.
First order of business upon getting inside and making sure it's clear would be permanantly reinforcing all the doors but the back one, I'd reinforce the back one too, but with pallets that can be removed with forklifts to allow exit. Second, use the cherry pickers they've got inside to get a couple of guys with rifles up to the roof and act as lookouts. Third, if all is clear, send a team out to the gas tanks to fill up the gas cans as much as possible, while another team prepares that fenced in area at the back to store the cans of gasoline. Fourth, get a group of people busy cooking, freezing, and preserving as much of the perishable meats and vegetables as you can. Most Costcos should have all the supplies needed for "canning". Get another group busy hooking up some of the gasoline powered generators and or Solar Panels (if currently in stock) into the freezers. Fifth, if clear, send a group ten out to the Lowes across the parking lot to load up on potting soil and seeds from their garden center. Keep making trips until you can't make anymore, or you've exhausted their supplies. Sixth, place several of the loading ramps just inside the doors of one of the loading bays. Should escape become necessary, you want to be able to toss open the doors, lay down the ramps, and drive right out. Seventh, pray you did enough.
If you are going to survive in their, seal off all doors with shelving, lock everything and reinforce it, then leave one door to get outside, then write in spray paint "All dead inside" on the outside to discourage and raiders to come inside, the fear of being over run with 40-50 zombies waiting to get out would be enough to make them change their minds.
Then make sure you can preserve the food in case the power goes out, RATION THE FOOD!!
Last thing you want is people killing each other in close quarters over a three musketeers candy bar.
A hardware store or outdoor store ((Lowes Gander Mtn. etc)). Plenty to board up with, ammo some food storage, fenced in outdoor area tall steel racks to make for watchtowers and they always build them near other shoping centers which makes for a double edged sword, food and people
Yeah and where exactly did you get this idea from… ha could it have been from me? And you didn’t mention that there are solar panels, skylights, kitchens, bottled water, bathrooms, plenty of canned goods, furniture and tons of movies and video games to keep you entertained until the zombie plague wines its self down.
I know that I am going to get a lot of crap about this but I would hole up in the local school food service warehouse. There are very few windows and doors and it's located on the extreme outskirts of my town. It's also large enough for an escape vehicle and there is plenty of food.
Being in Germany, There are steel curtains that roll down in front of the windows, called roladins. My current home is the safest place. Close all the widows, and arm myself at the front door. It's not impossible for a zombie to get in, but damn near...
One word. Wal-Mart. If you get past the fact that It would be Almmost impossible to takeover due to the fact that thier would probebly be a high consentration of zombies in the area. But it would have everything. You could find supplies to make nice barriors and ways to block off entrances, Guns, Food and water to last you years.