Make Sure You Don't Destroy the Foyer
You'd be surprised by how many otherwise intelligent people place orders for appliances that won't fit in their allotted space—assuming their new fridge, washer, or whatever doesn't get wedged up against the ceiling of the foyer. Appliance salespeople are full of stories about savvy customers who fail to note that the only way to access the kitchen is up a set of steep stairs, through a narrow doorway, and down a hallway that takes a sharp turn before dead-ending in a spot too small for its hoped-for purpose. Bring a map to the showroom with every single angle and dimension. If the salesperson seems to be not paying attention, ask for her home phone number so you can call at midnight to go over the measurements one more time.