I like the
Terry Fly CroMoly Gel so much, I have one on both my bikes. It fits my narrow, bony tush just right, the large cutout makes riding in jeans doable, and the gel takes the edge of city streets.
Conversely, the gel makes it unsuitable for all-day century riding. It's fine up to somewhere in the half-century or metric century range, after that, I just want off the bike. The local Terry rep was at the LBS last night when I stopped in and I asked her about it. She advised that something firmer, like the regular Fly, would be a better choice for centuries. So I may pick one up.