Here's a starship model I created. The base mesh was created in Groboto3D. Additional parts I modeled in Wings3D and Hexagon. All the pieces were assembled using Hexagon3D. I tried using 3DCoat and later Silo3D. But I find Hexagon3D is so much more precise for assembling parts on a model due to the fact I can manual enter in the x,y, z positions and rotation with numerical values via the keyboard. I think the same thing can be done in Silo3D.
I initially created this model a couple of years ago. But the base mesh close to 800,000 polys. I tried to retopo but gave up (too much work and not a very frustrating experience). I then tried decimating the model in 3DC's sculpt room. But it messed up the topology and the edge flow. So I then brought into Hexagon and manually reduced the polygons. For me, it seemed to work better and was so much more faster then retoping... It's now about 360,000 polys.
I now need to uv map and texture.