Can't be doing with proper cycle shorts, I just find them really bulky and uncomfortable. Have worn various makes of tri shorts at all distances up to IM and, while I wouldn't say I've been totally free of discomfort, they're a lot better than cycle shorts.
Should also say I'm happy with my saddle and it's usually just my sit bones which get a little sore on longer rides (80+) but that probably has more to do with not doing enough longer rides to harden them up 
<edit to add> Would never wear a trisuit in anything longer than a sprint - too much hassle in the (likely) need for pit stop.
Edited: 11/06/2012 at 20:17