I have an old Speciaized Body Geometry of some sort on my bike. I like it. It's good and comfortable even with shorts and normal underwear. BTW, as for the seams/chafing thing...I wear these seamless athletic underwear that I got from Target. I think they're from Champion or something. They breathe really well, and are good 'n comfortable even on extended rides. If I'm just out screwing around on a longer distance (25-30 miles) ride on my commuter I wear these underwear and they do fine.

Anything longer distance than that, and I ride the road bike, and wear proper bike shorts.