As far as I know, the 50" ChannelVision (CV) cans are the largest available. They are roughly 14" wide. In fact, the trend is now for even narrower cans, like 12". I think DataComm makes some of these. I guess the theory with narrower is so you can run wire on the outside of the can and just bring it in the sides.
Personally, I use the ChannelVision 50" ones. I also am not a huge fan of the Elk SWP-3. You can get more parts in the can by using a multipurpose plate like the CV c-308/9 and mounting components on those with plastic standoffs. The brass ones work well if you want to stack cards for even greater flexibilty like Electron did. You can see pics in My sisters install in the gallery, or just look at the
pics. Channel Vision makes a complete line of accessories and the Leviton stuff for the most part fits in it as well. Also, the Elk battery shelf *will* fit in the CV can. You also have the choice of a metal hinged cover, a flat plexi sheet cover or a nice smoked acylic door.