Shorts, shorts, shorts

Swim shorts, bike shorts, run shorts, tri shorts.....I am about to attempt my first triathalon, The Lavaman, in Kona. Is it best to use shorts spacificly made for each event and do a quick change in the transition area or is there one type of men's tri short that comes highly recomended? I have 2 pairs of Zoot shorts that are great when I run, but no matter how much I ride, my butt still gets sore when I wear them.