[cpollock]

I was wondering if there is any reason to choose a plastic film type capacitor, like the "orange drop", over a ceramic capacitor.  I've got a collection of each for 0.015 uf.  The ceramic caps are much smaller, at even higher voltages. I got the ceramics to replace the caps in the "bathtub" connector for the power line input, and when they arrived I was impressed by the difference in size from the orange drops I'm putting in for coupling.
I'm actually an electrical engineer and probably should know this, but to me, so long as it is non-polarized, it seems they should all be equivalent.  However, there is art in electronics, especially in tube electronics,  so I am curious if there is some reason to choose one over the other.  
Thanks!
Clif