Sounds like My wife. A 15 minute trip to Walmart turns into the quest for the Holy Grail. The cane might work, but like Benny, I would probably swat the wife with it and tell her to hurry up... 

My alternative is drop her off at the door, find a place to park so that you can watch the gals...er people, yeah the folks going in and out of the store, crank up something good on the satellite radio, get the seat laid back a little and wait..and Wait..and wait.. 
 
 
Glad the cane is working out, I have one that my father in law made. It does help when I do have to venture into that place..Another quick tip for the Walmart trips..They usually put the sporting goods and man stuff over by the Auto Center. If you absolutely have to go in, park around there and go in through the shop...It saves going through the miles of women's clothes, card, houseware..etc...straight shot right to the Wallyworld Man Cave.
Keep Kickin'AS
Chris