I've had Bryce renders run that long.  Luckily for me, I have machines that I can just dedicate to a single render (I prefer that to the render farm approach).

What cracks me up are those times that I've just finished up a 30 hour render and then notice something that is just not quite right with the thing .... and so I tweak it and back in it goes for another 30 hours. 

Could be worse, could be raining.