Side by sides usually aren't used because you can't fit too many cornies in there even though it's a big size. The space inside is long and thin and you can't stack cornies on top of each other. Another thing to consider is you'd have to stack them back to front on the floor of the fridge, and if you blew a keg in the back you'd have to disconnect all the lines to get the keg out. A pain, I'm sure. Before you drill anywhere, do you have any kegs? If not, get some, and see how you're going to stack them in there.
Regardless of what fridge you use, don't keep frozen glasses in the freezer, keep all your yeast, hops and grains in there! It'll keep the SO happy, for sure.