Retailers don't need to be told how important in-store merchandising is. The better ones see the collective sum of all of their stores as being more important than the total value of the individual products themselves. To them, my hat, if I wore one, would be off in salute.
Take a moment and think about one thing the overwhelming majority of consumer electronics products have in common. Save for the odd clock radio, everything you sell only works when connected to something else. Everything. Speakers, monitors, DVD players, PCs, external hard drives, car stereo head units, A/V receivers, amplifiers, MP3 players and so on. These CE products only work when used in conjunction with an almost endless list of accessories including everything from cables to batteries.
Think of your in-store merchandising as a wagon wheel, one whose outer ring represents all the primary products you sell, all inter-connected to each other (remember almost nothing works by itself). The smaller, inner ring includes the accessories the customer needs to make the primary products work, including training (another product for you to sell). The arrows indicate that customers can enter your store at any point on the wheel, which in reality they do. (One day they come in interested in flat-panel TVs, a week later they come back looking for printers.) Each time their mindset is different, as is their knowledge about each product.
Once inside your store they can and should be encouraged to move along the "wheel" to products that are related to whatever caused the initial visit. For example, customers should at least begin to think about improved home audio for their new flat-panel TVs, or wireless distribution of music files residing on their PCs. How you merchandise your store will encourage them to do this — or ensure that they don't.
The alternative to wagon wheel merchandising is what is typical in many stores. Blocks of products that are at best physically adjacent (though often not) to other products required to make them function, such as loudspeakers near A/V receivers or printers near computers. When you do that you presume, often incorrectly, that consumers know what they will need to make it all work. But trust me, they don't. They weren't born knowing they need to consider the critical accessories necessary to put it all together — a fact to which those who bought a printer that did not include a necessary cable can attest.
So do fret the obvious big stuff such as facility cleanliness, paint, fixtures and so on, but in addition to that take time to think like a consumer. You sell products but they buy solutions, the "collective sum" of what you offer for sale.