I am suprised that you don't see more people pulling trailers with living quarters to cattle shows. We show both cattle and horses, usually only the county fair and another small show with the cattle but lots of horse shows. Our cattle trailer is a 7 1/2 x 20 with a 4 foot dressing room, I really like the dressing room becuase we can keep our fans, showbox, and other show stuff on the trailer all of the time, it's loaded and ready to go when it's time to show.
Our horse trailer is a 7 1/2 x 26 three horse. It has a 3' midtack for storage and an 8' short wall living quarters, we have a bed in the nose, a dinete that converts to a bed, microwave, heat, ac, shower, toliet, cabinets, and a closet. Everything we need for showday is in the trailer....paperwork, cloths, snacks, drinks, etc. It is nice to be able to get out of the heat or cold to change or just take a break, nice to have your own bathroom, just nice to have a little place to keep organized while we are showing. We also spend several nights a year in the trailer for overnight shows. If we went to more cattle shows I'd probably take the slants out and use this trailer for the cattle shows....so I guess to the subject of the ultimate show cattle trailer for me it would have a living quarters, something like this:
http://gc4star.com/trailer_details.asp?id=%7B461FF492-2B26-436E-8213-CF16ACC36829%7D&icn=31250&cls=116&cat=123