Think of a home improvement project, write a ton of notes, cost, draw plans, whole ball of wax..if you have a cork board and yarn use it. The more deranged the better.
Drag her to Home Depot and wander aisle to aisle looking at EVERYTHING and jotting prices and UPC numbers. Ask lots of questions of everyone there, employees and customers then cast doubt on their expertise.
Make sure to take as long as possible keeping her on her feet and a little lost...the game here is to pay back every shopping mall moment in one blow. At the end of the trip buy some tool or material in the 200/300 range (but not on your list).
Do it right and you will always have time and a excu$e
[*you can not substitute with Lowes, the layout and people will turn the tables]